Consider adding role spell lists like in D&D, in which your role dictates which specific spells you can learn. If you would successfully read a spellbook whose spell isn’t on your role’s list, you get told “[Your role] isn’t allowed to learn this spell”, similar to the message for twoweaponing. This could be extended to races and alignments, but extending it to genders would probably be too silly.

A simple initial way to do this would be to make each role’s special spell exclusive to that role.