I mean like, she has alot of weaknesses, while having powerfull magics. She cannot take hits good at all, she doesnt even want to hurt her opponent, even when she has to, she is reluctant to do so. The only way she can possibly fight is if some other being ( the demon) helps her do so. And if your character has any kind of holy magic or weapon, or a cross, shes completely on her own, and pretty much screwed. And also, not neccesarily overpowered, because she can only exert as much magic as her body can handle at one time, being small, fragile and young can hinder her ability to do a significant amount of damage. Also, being young, she must exert great focus to use her magic in direct offensive.
And if you still fo not agree with this
@Rilla, i could change it to where she has relativeley weak magic, but can use it often, and can hold duration magics for extended periods of time.