Lv 5 magic is pretty powerful stuff, I almost never get warriors, (nvm Assasins/defenders) who are as good as magi. I like how champions lv slower but do think that low lv champions you hire should start with more traits.

I Agree that there should be some more ways to add new schools to magi charcaters as well as quests that reward unique traits.

more like terribly crippled

This is a valid problem that will most likely be solved. You see, you are not leveling because the AI can not compete during a war. Wars generally are decided at some time on one turn where you meet the AI's stack of doom/pioneers and kill them all, leaving its cities open for conquering. When the AI gets better, so will leveling. You just need to be fighting more battles. Of course the monster spawn rate needs to be increased across the board too. I am playing against some very dangerous lairs in my game. I can usually get four to five mages to level 10 by the late game. Hope they tweak some of the lair switches in the next beta.

I forget which turn it was, but I remember like 30 spiders spawning in an unused forest in the midgame. I had to make peace and send my best armies back to fight a spider war. It was great fun.