Yeah, I agree. Aerie is by far and away the most versatile of the spell casters. I still think Edwin has the most punch of the mages due to the sheer and ridiculous amount of spells the guy gets. If your still looking for a mage, then Imoen still tops Nalia. Better thief (Imoen handles all your detecting traps and picking lock needs just fine but cant do much of anything else), just as good a Mage, and much much much less annoying.
Besides, shes your sister man