In the game(s) mages always seem to have low health. Maybe that could transfer into this somehow? They don't usually wear any armour. They're not combat trained in the way that warriors or rogues are... Just ideas, but if done right that could certainly be a flaw in that she would have to rely on others in battle so as not to get killed. More so than average I mean. I suspect we'll all by relying on each other in battle.