1. Threaten and Taunt is level 4 talents, first you must learn Powerful and Precise Striking. Which mean at level 3 you only have ONE weapon talent to learn before you can tanking, in which it is not enough for tanking. While you are at level 4, you draw aggro but you can't hold it with your current weapon skill.
You are a low level Warden without a lot of points in strength or constitution yet, or you have no experience with leveling up (if the person in question is playing for the first time) so that means you have to rely on teamwork. Archers like Daveth at first, using Jory to rush in, and wade in shortly after, and just generally fight smart while you get stronger. Nothing broken about that.
2. Two Handler for off-tanking, all the talents are not for tank, only Sweep give you AoE melee at level 10, which mean originally Two Handlers is suppose to off-tank because there is no defense and escape mechanism other than Sweep at level 10. All other skills are for 1 vs 1 duel. But funnily Two Handlers got 1 talent that suppose to a tank talent that is Indomitable. Two Handlers don't need it much in off tank. Weapon and Shield is supposed to have Indomitable.
Two-handed fighting wasn't originally meant to be for tank. But for huge damage dealing in single strikes. The fact that they wear heavy armor helps them take hits, but they are meant to do far more damage, or damage to multiple enemies. The fact that they can knock down multiple enemies in a single swing helps out with that. Again, not broken.
3. You draw aggro in early game, the enemies surround you taking turn to use Dirty Fighting or Shield Pummel, some of the enemy using Bash on you, as a tank you can do nothing to handle the situation, you will rely on your healer to heal you in which you don't get healer early in the game. You just a sitting duck there. In higher level, archer enemies also have scatter shot, then your tank is suck. In 5 seconds you dead.
You also fight low level enemies early in the game. Red named bosses doesn't take place until the Ogre at Ostagar on top of the tower of Ishal. Again, a little teamwork at the beginning goes a long way to keeping enemies off of damage dealers. And health poultices exist for a reason. yet again, not broken.
4. A tank should be fast build not slow build, because a tank job is to hold down enemies, taking or blocking damage and stand ground. What the hell a tank build slow? That is a bad mechanic.
Because the level your enemies fighting you at also go up slowly. And you can always use other teammates abilities to single enemies out, stunning shot with an archer to take an enemy temporarily out of the fight, stasis from creation mages, grenades and acid flasks. The warden isn't the only one with abilities to even out the fighting and that allows him/her take a lot more damage.
Yet again, not broken, just a gameplay mechanic you disagree with.
5. Feign Death should not be the last perk in Rogue tree, it is because the player have build their rogue character to be able to stand in combat, no one use Feign Death. Don't lie to me, Feign Death is just a waste perk. It suppose to be the first perk not the last, because when you are strong, you don't need to fake death. That is broken.
Rogues can also learn abilities like stealth or poison faster than a mage or a warrior, thereby getting more of them. Why can't a rogue use stealth, get behind an enemy, and then start hammering away? Or use their many abilities that stun or hinder enemies movement speed or attack speed to help? Again, gameplay issue, not a broken mechanic.
6. In DA:O, the combat is always mob fighting, but the game doesn't provide the proper mechanic to handle it. 4 person with tank, dps, nuke and healer tu run against mob. Each mob deal X damage, stun and bash to a suck tank, the tank can't hold it, Two Handler off tank is too slow, backstabbing Rogue and haler Mage are too fragile...when tank down, all down. That is broken mechanic. Just try out Denerim Back Alley early on.
But if the gamer uses all the talents of a well-rounded party, even group fighting becomes laughably easy. Traps, mass area spells, grenades and poison flasks, poisoned weapons, stunning, knocking over, general skills of a well-rounded party once again makes up for facing a lot of numbers. Gameplay mechanic and a battle system meant to fight smart with tactics more than brute force. Not broken.
6. Alistair is an anti-Mage, at the same time he suppose to be a tank, but he don't fit both in early and middle game. His stats is to low for a tank, and he only have 1 talent that is drain mana in which useless fighting mages early on. He is a total mess. The Hurlock Alpha in Korcari Wild give fireball and he can do nothing as an anti mage. The same with against mages early on at Circle Tower, or in the ruin at Denerim. By the time he have other anti-mage skills, there are not much mages anymore in the game, and mages are not a threat anymore. Not only that, he suck at tanking. Alistair is the perfect example of broken mechanic.
Have him attack a mage quickly, have one other warrior in the party (Warden or Sten), one rogue and one mage, and that's usually more than enough to keep the entire party alive most of the time while you level up. Once again, a gameplay mechanic and not broken. It was designed to think about what to do before entering battle, not expect everyone to be the best at it from the beginning. Again, not an issue. And once again, health poultices exist for a reason.
Not broken. Just not what you are used to. Granted, if you play DA2 before Origins, I can see why you would take issue with it, but DA2 came after, so the combat was improved.