She wants to the power to kill with her own hands, but that doesn't mean that she will use it, just make others know that she is able to use it if it comes to that. Strength is not a bad thing, it's the way you use it, and, obviously, she does not want to use it in a bad way. If she wants to use it to intimidate people, that would not be good, I agree with that, but if she just wants to have it so that she has a talent that come in handy (self-defense), that's fine.
~Another random thing from another forum-thing~