OK, I love the concept.
Few things:
In Description: What is a "hungry Yamataian look?"
In History:
1. Is the memento the depression in her nose?
2. The likelyhood of a "rogue" Neko at the time she was getting training is pretty unlikely. If she received it later, say, when the NH-17 was around, it might be more believable, but the timetable here makes it sound like she was getting trained by an NH-7, which are less likely to slip through Yamatai's grasp (especially into Elysia).
Also, why just melee weapons? That wouldn't make sense if the instructor was trying to train them to use the "weapons of their enemies." Kids might not stand a chance against a more powerfully physical opponent in a melee fight, but a kid easily can shoot a target at 200 meters β just ask a child soldier in Africa.
If you're looking to justify a melee-oriented character, just say she favored those weapons and sought more teachings on them.
This character is pending.