Or you can overwhelm him, with tremendous damage output(at least 2x more damaging, faster, less stamina hog power attack, and with enhancements on both weapon), and plus there is manoeuvrability of dual wield.
I don't even mention potions.
Lol, yeah right, show me how you "overwhelm" the frost troll on the path to High Hrothgar at the beginning, unless your just talkign at high levels with powerful gears, or on low difficulty, than yeah, it's super easy with dual-wield, but so is it with any build, my high level 1h+shield can just stand there all day taking a beating, but that doesn't mean I could do the same while I was trying to get to that point, I for sure remember how that frost troll could 1-2 shot me. Are you even playing on master as you claim ? or you just decked your toon with dual wield late game, cause you won't "overwhelm" any of the tougher enemies until later in the game.
Also your still missing the point and avoiding the question of how it gives your better survivability. As the only thing dual-wield can do that makes it do more damage is power attack which leaves you open to counterattack(if it didn't stagger) or just plain beating from other enemies as you have to be close, and even if you were to use maneuverability and use normal attacks, you would just deal less damage than a 2h and have to be closer. Also the extra reach of 2handers actually makes up for the slower animation, as you are already further away so you have less distance to travel to avoid the attack, and if you weren't you could just bash.