Not sure about destruction will have to respec to check, but magic enchantment works on spells, and int works on weapons magic damage, just like str does for melee. I just got a 75 magic damage two hander and its adds 90points of damage to each missile on magic missile spell. It has no int or anything so kind of wondering where the extra 15 points of damage are coming from, I decided to just use a two hander with her, cause dual wield with two of those enchants just makes the game too easy, even on nightmare. Lost a hundred mana from my old maces too, but yeah i want a challenge this time. I have very little hit points so i get killed in two hits, but i kill so fast so it's really exciting. Very different plays style from warrior.