Wouldn't it be better like this:
I: 2 uses of magic per turn
II: 3 uses
III: 4 uses of magic per turn
IV: 5 uses of magic per turn
This would improve the balance.
I: 2 uses of the spellbook per turn, the first spell can only be level 1.
II: 2 uses per turn, the first spell can be level 1 or 2.
III: 2 uses per turn.
IV: 3 uses per turn.
The ability could be gained, for example, when the Academy's troops are idle.
But the faction abilities don't work that way.
