I like her design, its simple yet cute. I do wonder what the bat thing is. It looks kinda cool, probably hurt if you'd get hit by one.
That would be a Tetsubo, a traditional Japanese anti-armor weapon commonly associated with oni.
Actual Tetsubo were usually made of wood with iron studs, but oni are usually depicted as being inhumanly strong, and so are commonly depicted using tetsubo made entirely of iron.
