So finally got my enchant skill to 100 and can't decide which two magic schools I should have reduced significantly (don't want zero cost because game loses its fun then). Right now my character uses destruction, restoration, and conjuration. I can't decide which to reduce costs on or if I should reduce destruction and boost my magic regen to over 240?

Sidenotes: the forifty magic skill and magic regen enchants are completely useless it seems unless someone has found a good use. Also why can't ancient nord amulets be enchanted??? If you don't know what this is its a amulet is a glass display case in the jarl of falkreaths bedroom. It looks cool and I would like to enchant it, so is there a way?