Shields are OP ?
I red quite the contrary...
I never really tried them, except on my mage, but with a shield you loose DPS for more survivability, in a game where dealing damage as fast as you can is more important than tanking.
So yea I know there is a shield bash skill that is super powerfull, but it has cooldown, and I'm not sure it is worth it to make such a character just for one skill.
Anyhow, I'm not trying to say you wrong by saying shield > 2H, quite the contray as someone who only played 2H, I want to know if I was not mistaken and if shield isn't in fact better.
What I fnd weird, is that shields might benefit more from classes like mages, who are really not the traditonnal bearers.
Don't forget the grenades, there is a talent that lower their AP cost if you are playing a one handed character, and 2H are strangely considered one handed for that talent.
So also consider that for 2H, it makes them even better.
But then again, rogues should be the natural users for nades, and they obviously aren't in this game...