At the moment, it is not really a question of it being "effective" or not. It is mostly desirable due to immersion and rp reasons. As for the "Parry Stance" thing, it is already implemented. But the issue is not the defense, but the actual use of the weapons. Holding a sword in main-hand and a wand in the off-hand, the character will act as if the wand doesn't exist, and vice-versa.
