For starters, make clerics, abjurers and healers whole separate issues.
Well, the idea I have shortly: Make healers learn spells from books (for certain-%) before letting them to study them at the guilds (something similar to dragon lord scrolls)
Then make all spells masteryspells.
Third idea would be to make cleric/abjurer prof-guilds combined to the two previous.
More to come... maybe