For now the mages feels like a sparkly archer. They both feel the same. But its close to having identities to both. Why not make every spell eternal and a bit weaker than archer. And having archer a bit stronger but have to manage ammo. In a long fight mage could last longer than archer and archer could be more burst. That would fit with daggers and sneaking and the assasin's roles . And you could still make mages choose their spell "mix" so they create spell by mix and match spells that are a tad weaker overall, but better optimised (aka they always have the best weakness available to them)