Sorry, but if the game is based around magic, and you can't start out with stronger magic, the one who knows more different spells is going to have an enormous advantage over the one who knows only a few.
There are actually
two systems to the game. The advancement in power (through skills) is one, acquiring spell formulas is the other. The second one is purely self-limited by you players. No game mechanics stops you from having a collection of a hundred spells a week after starting the game. You probably won't be able to use most of them since your skills aren't that good, but your opponent with 20+ skill in everything can't harm you one bit unless he knows a harm spell or two.
