Her cutesy and happy-go-lucky appearance stop at her looks, as a much less sweet disposition hides behind that face. As she loves to wear long-sleeved tops with a skirt and thigh-highs, she can very easily conceal a weapon, and does. She wears a small garter-like holster for a butterfly knife on her upper thigh and under the skirt, meaning that you won't really see it (and if you do, looking up there is excuse enough for her to pull it on you)
She's unreasonably skilled and quick with said knife, as she seems to have much experience wielding it. That, and she can be extremely defensive, makes a tough combo for anybody with romantic intent to approach her without being gutted.
Rumors occasionally pop up that she gets really lonely with that kind of lifestyle, and that she may be temporarily softening up to others, especially boys that want to get with her. She denies that that's the case, but you would have to find for yourself if the rumors are true.