Really? I kind of figured that Swordmages would pick just one option and stick with it.Have you seen the Swordmage in the FRPG? He can't use shields but he gets a +1 AC when fighting 2-handed and a +3 to AC when fighting one-handed (other hand empty). I read that and thought "Oh, that's who's using all the versatile weapons."
I mean, lets say you're using a weapon in one hand. Odds are its versatile because its a military weapon held in one hand, and they generally are. Probably its a longsword. So, you have a choice now.
1d8+stat+enhancement damage, and +3 ac
1d8+stat+enhancement+1 damage, and +1 ac.
When is +1 damage going to ever be worth -2 ac?
More likely, you're going to stick with the one handed option. And if you wanted to go for the two handed option, you're wielding a greatsword or a glaive or something in order to get the full benefit of both hands.
If the rule was something like, "gain +3 ac when fighting with a weapon in one hand, or +1 ac and +str damage when fighting with a weapon in two hands," you might see a trade off. Except then it would get abused by people using glaives and greatswords, so you'd have to restrict it to just the versatile wielders.... putting us back where we started, with needing a new build for versatile combatants.