So I ran Several Tests and come to the conclusion about Several things on Two-handed warrirors and decided to discuss it with everyone as well as offer and accept advice on things.

Couple things starting out.

1) If you want to build a two-handed warrior chances are you are going to be using a lot of skills. Will power to a decent level is a must and you need to time your swings not to waste an effort.

2)Gear is very important, two-handed warriors are somewhat crit-dependent. I'll go more into that later, but Armor rating isn't everything. It may be more beneficial to stick to lower end armor such as the Medium Armor Varathorn's Armor which gives you +50 Stamina, then it is to wield something much heavier with less of a boost. This is especially important on the hands, helm, and boots. In the case of those having light armor or having massive armor is only a difference of 2 armor points. Sometimes the damage increase is more important then the armor quality. If you must have high armor make sure you focus on the main body armor as it gives you the most bang for your buck in that area.

3)Don't waste skills. Your going to hit hard, very hard. If an enemy is 1/3rd dead a normal swing will kill it, no need to waste precious time with a skill unless its an enemy that you want to make sure absolutely dies on the next hit.


Weapons:
Axe vs Sword vs Maul
I've ran several tests on various weapons, and I've come out with this Starfang and Chasind Great Maul are equal in DPS. They'll have their variances early on, mostly maul will do more damage until a sunder armor or other armor lowering affect is placed on the target, then Starfang will win. But Starfang is also more accurate early because of the +attack so your less likely to miss if you see that is a problem. Testing Axes I was overall unimpressed. They do however Crit a lot more often which if you are a large fan of Sunder Arms they may prove to be more to your liking, but they lack the power of a normal hit, or even a critical hit, from starfang or the great maul.

Summarize:

Great Axe: Good if you intend to only stick to Sunder Arm and Sunder Armor, the additional crit will make these produce high crit value over a long period of time, not good at all if your playstyle has you using Mighty Blow or Critical Strike a good deal. But blow for blow not as strong as a maul or sword.

Great Sword: Has a great bite to it and a decent ability to crit. Overall I'd say these are the better weapons once you gain the ability to damage armor.

Great Maul: Punches through armor and has a high strength modifier which can lead high damage on heavily armored mobs such as dark spawn, guards, and skeletons. Poor Crit rate which means this weapon is better for people who prefer to use Mighty Blow and Critical Strike over Sunder Armor, which actually makes little difference as they eat through most enemies armor.

I'll focus on abilities now, but I'm going to mainly focus strictly on those in the two-handed category and not warrior abilities.

Only two abilities I'll make not of are powerful which gives you extra HP and lower fatigue a must for any warrior and Precise Striking while it lowers your attack speed it greatly increases your chance to crit and your attack. Since most your damage is coming from your skills which does not care about your current attack speed and will only move at the speed of the animation, the end effect is that your abilities hit more often and will crit much more often

Abilities..

Chain 1- Critical Strike Line

Pommel Strike - One of the most underrated abilities you can have. It knocks your opponent to the ground It won't deal damage but it has an incredibly short cooldown and can keep troublesome targets like mages on the floor while you beat them to death. Great for interrupting heals or killer spells. Also if a target happens to have high evasion in the lower levels and you can't nail it, well that evasion will drop like a rock soon as their on the floor. Not used to kill, but is a great form of single target crowd control.

Indomitable- This is why most people love two-handed weapons, it is one of the most powerful abilities in the game. It increases your damage by a small amount but most importantly it makes you immune to knockdown and stuns something you'll see a great deal of later on. Its only downside is that it costs a large amount of stamina to maintain which will make it unwiedly to keep it on early on in your life as a two-handed warrior. To compound to this, stuns and knockdowns are not very common till later on in the game. In the end great talent, but something you can skip early on. You should have it on 100% mid to late game however

Stunning Blows - This is a very powerful ability, causes your attacks and skills to have a chance to stun, it however does not trigger on all of your special moves as it will rarely if ever trigger on Sunder Arms or Sunder Armor. It has an extremely high chance to trigger on mighty blow and critical strike though.

Critical Strike - Basically a critical strike with an attack bonus behind it, it seems to do slightly more damage then a regular critical but I haven't tested enough to verify this. This ability is great early on outright killing most archer and lower level mage targets. It has a very quick animation and since its prerequisite is stunning blows it by default will always have a chance to stun the target. Pommel Strike followed by a Critical strike can almost always insure a target is disabled long enough for you to kill it.

Chain 2

Sunder Arms- I personally never liked this ability much. It will strike twice but over a long animation and lower an enemies attack rating, it is quicker then two normal swings, but any ability that boost swing speed will cause this to loose power. I.E. If your using swift salves a great deal or have a mage with haste on the party, this ability looses its favor quickly. It is great with an Axe or a sword, the attack penalty is negligible by most standards though and is really only a good ability for its ability to strike twice. Interesting affect if you kill something with the first hit and theres something close by it will hit the other enemy with the second. It often misses on one of its hits if you used it to follow up a pommel or any ability which knockedback or knockeddown the target. Remember this, if your party setting has a lot of these abilities it will decrease the usefulness of this ability.

Shattering Blows - This is a very niche ability, it does affect a few things in the game. It gives you a damage bonus against constructs and golems. Its nice against golems who have very thick armor and you want to grind more points of damage into them. But they are a rare enemy. I'm not exactly sure what all constitutes a construct though. Skeletons I find are not constructs though someone had mentioned they counted. The sylvans might however. Ogres do not.

Sunder Armor - This is an awesome ability all around and one I profusely use. It has a low cooldown and will strike with the same animation as sunder arms. It for some reason does not have the phantom miss with sunder arms that happens every once in awhile and the attack punches through armor and leaves an armor debuff on the target. It is a must for Sword and Axe users. The ability has a chance to crit twice, one on each hit.

Destroyer - This is a very iffy ability that will lower a targets armor on all hits from your weapon, it isn't as strong as the debuff granted by sunder armor and is almost completely negligible if you use a Great Maul. It does help swords and axes as you may not always have sunder armor off cooldown when you need to kill something and this will garuntee that it will get an armor debuff. Pick this up if you are intending to have mages with haste in your party, however. I will go into more detail why later on.

Chain 3

Mightly Blow - Basically a guaranteed critical blow that will pose a movement hindrance on a target. For all the bad press this ability gets its not that bad. It has a bit of lag in the beginning of its set up so it is not an ability you wish to lean on once you get Sunder Armor, but it can help early on in the later difficulties. This ability has a very high chance to stun if you have stunning blows, which means it can be used to help disable softer targets, it also puts a movement hindrance so they can't run away from you while you lay the smack down, something that always irritates me when you go after a squishy and they start running away. Between Mighty blow and Pommel you can keep a target near disabled while killing it with Sunder Armor. Warrior version of the Rogue stunlock.

Powerful Swing- The Love/Hate of the Two-handed Warrior. This ability gives you a massive boost in damage, much greater then that of Indomitable, however it comes with a penalty to attack and defense. Now remember I mentioned that you will be using a lot of skills and that precise striking will increase your crit rate and you won't notice the lowered attack speed because you'll be using skills between swings? well guess what the attack bonus granted will completely negate and still bonus the penalty powerful swings gives you. I will still suffer a drop in defense. This is meaningless overall since as a Two-handed Warrior you should never bother with dexterity which means your defense is pretty much tanked to begin with. Your not going to dodge that hit anyways, no sweat of your brow. 

Two-handed Strength - Basically improves Powerful Swing, you no longer have a penalty to accuracy and get a reduced penalty to defense, still have to muscle through a -5 penalty to defense, but like I said you weren't going to dodge the blow anyways. If you plan to make a high dexterity two-handed warrior, this would be a pain. But you also wouldn't be maximizing your effectiveness.

Two-handed Sweep- Wide Arc AoE attack. I recommend it for almost any two-handed warrior. If anything just for the large damage and knockback it does. Despite the animation it is not a 360 degree attack it will completely miss things behind you. It does go more then 180 degrees and will hit things off to your flanks though. Great ability, low cooldown. It does have a wind up, so one good tactic is when you see the enemies charging into you when they are just a bit away strike, that way soon as they clash into you the first thing they feel is a blade smack em straight back on their butts before they even land the first blow.

Runes
These can be funny things, if you chose to be a two-handed templar I would load up on spell resist just so you can laugh at mages. Passives will be more effective here then +damage bonuses unless you play a dual-haste mage style. I wouldn't worry about physical resist, most physical resists are knockback/knockdown which you pretty much are immune with Indomitable. I personally just put three paralyze runes in the weapon. When I wasn't using a skill I wanted to make sure it would either stun by stunning blows or paralyze. You can put damage runes here, but you won't see any noticeable difference unless you use a very specific playstyle, more in detail later.

Specializations.
Templar- Really doesn't give you much, you will on average have higher will power then most other warriors so you can use Holy Smite to more effect, but the damage increase isn't all that great. Righteous /strike will not do much for you because of large intervals between swings. It will however give you excellent spell resist armor, you don't even have to put a point in Templar abilities just have it selected as your spec to do this. You could go champ then templar, not put a single point in it and get spell resistant armor.

Champion- Nice buffs, another knock back, boost to defense and attack. It has a downside, it gives a great buff at the expense of a large chunk of stamina. You should have 3-4 sustainables up as a two-handed warrior so this is a no-no. If given the choice of a few extra points of attack or extra damage from lets say, powerful swings and berserk. You should go for the combo of the later.

Reaver - This is a bit of an oddity. It gives you four abilities which don't really play into each other. The first ability will save you on health poultices, its got a low cool down and since you'll be making bodies you shouldn't be that far from a corpse. Frightening Appearance however is great, and will usually paralyze a target completely. Great for holding something in place while you kill it. Aura of pain does little damage, but what you'll often find is that you'll often hit something to within an inch of its life, a little plink from aura of pain will usually push it right over. Its low damage but the constant aoe dot to everything around you can help kill things. This is comboed good with Blood Frenzy which will increase your damage as your health drops. You'll flirt with death just as it says though and the increase in damage isn't always worth the corpse you make out of yourself. But you can use it to increase your damage while something like Berserk is on cooldown and your waiting for it to reset.

Berserk - Pretty much what you want to use if your a two-handed warrior. Increases your damage, but stunts your stamina until you improve it. Gives you a health regeneration so you can keep in the fight a bit longer which will help your healers a bit. Doesn't cost much at all to maintain which is a great bonus as well. Final Blow is interesting. If you get it early at stack +stamina gear it can be a devastating strike, but it will drain all your stamina and disable berserk and indomitable(which I think causes a stamina penalty because of this).

My Opinion Pick Berserker/Templar if you want anti mage or Berserker/Reaver for just a bit more damage. Stay away from champion because of the penalty of having another sustained. If your running a Dual-Haste mage set up then Champion may be a good thing to use however.

DLC
Warden's Keep will give you some great things here, most importantly Starfang its the only sword that can keep up with a Chasind Great Maul. Warden Commander gear is also great in that both the chest and the boots will give you great stamina regen on the chest gear and +50 stamina on the boots.

Most importantly the new abilities
Blood Fury will sacrifice health to knock everyone back, can be a last ditch effort to get some breathing room but you won't use it much. Two-handed sweep wins in this department. 
Blood Thirst however, is probably most powerful in the hands of a two-handed warrior. It increases critical strike chance by a great deal, improves swing speed, and increases movement speed. You'll suffer a health drop but you will crit much more often and swing much faster, these things are very important to a two-handed warrior its a noticeable difference in overall dps. Makes things like Sunder Armor turn into the hand of god.

Stone Prisoner will give you the harvest ring one of the best melee rings in the game, Helm of Honneleath is a powerful item but Executioner Helm will almost always be better for a two-handed warrior.


That gotten out of the way there is essentially Three ways to play a Two-Handed Warrior.

Hasted- With atleast one mage with haste and blood thirst, your inbetween swings even with precise striking slowing them down are much faster than the two-hitting ability of sunder arm and sunder armor. Using either is a waste of time. Critical Strike however is still worth it, so is Pommel Strike and Mighty Blow for disabling. Since you won't be using many abilities and Critical Strike has a long cooldown it is okay to use poisons and +damage runes. I find it a waste personally to have dual-haste mages but some people will find it very useful. Sword is overall the best for this particular set up.

Sunderer - This build is better with an Axe or a Sword as it basically rely on a high attack power and high critical strike rating. Precise Striking is almost a must for this build. You will still be using mostly your abilities but will instead rely mainly on Sunder Arms and Sunder Armor. Focus your gear on anything that increases your critical strike rating above anything else, shadow belt, katriels grasps, ect. You want to make sure that almost everytime you use either ability you will crit. Mauls are rather horrible for this because they have low crit rate.

Unstoppable Force- This build prefers Mauls and Swords, it will rely mostly on abilities like Critical Strike, Mighty Blow, Two-handed Sweep, and Sunder Armor. Your basically doing your best to keep everything around you off its feet while you smash it to bits. Your main abilities here are Critical Strike and Sunder Armor, using mighty blow between sunder armor cooldowns.. Try to open on groups with two-handed sweep. Mauls will punch through armor which will give you a higher dps, because of your reliance on critical strike and mighty blow to soften targets you by pass the weakeness of the Maul entirely. Sunder Armor is still one of the best abilities so you will still use it between to deal damage. Critical Strike -> Sunder Armor, usually leaves nothing but a poorly damaged body, executed much quicker then an attack -> Sunder armor would go off.

The last two do not require haste or swift salves at all to be effective.

Stats

You should train mostly Strength and a touch of willpower. If you feel yourself a bit squishy you can train a few points of Constitution but in all honesty good amount of poultices and proper healing you'll be fine without it. I'd leave it at your discretion on the constitution. You should never, ever, bother with dexterity however. The most you should have is 18 and thats only if you plan to max out the second chain of the warrior build for the massive boost to attack. That said, going to the mages tower will give you 18 dexterity to accomplish that.

Get your willpower up earlier rather then later. Early on in the game you'll have more strength than any armor or weapon available to you will really require you to use. Use this time to bolster your willpower so you can keep your sustainables up. You should have enough that you can keep up Powerful Swings, Precise Striking, and Indomitable 24/7 without a problem and that turning on Berserk and Blood thirst does not gimp or bother you in the slightest. I personally brought it up to 30, then poured the rest into strength. Strenght is both your ability to hit things and to bring them pain, your weapon has a larger modifier to it so use it, and it will pay you back tenfold. Whatever makes you comfortable is up to you, and you should really get a feel for it on your own.


Suggestion on gear:
Without going into expensive things like getting a Chasind Great Maul, you can still get pretty good gear cheap, Meteor Sword and Thorvil's Luck(maul) is available early on in Denerim from Gorim. Faith's Edge(axe) drops off a semi-optional boss in the Ruined Temple in Haven.

Executioner's helm will give you +50 Stamina which will eat up almost all of the cost of indomitable and provide you with decent armor till the end game. If you get access to the better goods from the crows you get a dragonbone version from the crow vender.

You should go to the dalish camp early, not to do the quest so much as to get access to unlimited elf root and you can do atleast one quest without going to deep in from Varathorn which will give you a very good set of medium armor with +25 stamina on this. 

You can also get the Warden's Keep DLC for some nice boots that give you +50 if you loot them off of Sophia's body and use the chest there to level up some of the gear that drops if you get it early.

Using the three items Mentioned above you'll gain +125 stamina. Using a great maul thats a +200 overall stamina you can get from these items which is more then enough to stack several sustainables for massive damage boosts and use all your abilities and still be only half way through your stamina bar. Its rather ridiculous and fun. This plus a ton of +willpower items, and running up to a mob and lashing on a final blow is rather fun and easy way to get the heavy hitter achievement.

Later on in the game getting Superior Dragonscale Armor(heavy armor) is one of your better options as the complete set gives you +4 stamina regen in combat, which will allow you to replenish any depleted stamina rather quickly.

Katriel's Grasp(gorim again) and Shadow Belt (WK dlc) will help you increase your crit rate if your relying on the different sunder abilities which makes for a good deal.