You can't block if you have one handed weapon and a spell? I thought blocking was a huge part of survival in Skyrim? Sounds like instant death to me, unless there is a spell to physically block melee attacks. Maybe this makes sense from a balancing perspective, but I'll have to wait and see.
I am interested to see the button-mapping for blocking depends on the weapons you are using, because I'm glad you dont need to hold both triggers to block for every weapon. It raises some questions though...What about unarmed blocking? What about just one weapon? Will blocking be LT for one weapon or will there be no block unless you have a shield? (i hope not).