Probably no "charge" at all... it was likely just to keep her skill consistent and show she was supremely talented fluff-wise as they specifically avoided giving her any type of missile weapon in 5th. And she's not the first CC only character in warhammer that was given a balistic skill even though there was no way to shoot. Every once in a while, they wise up and just give them a 0 to make sure, but usually just give them the same stat for looks.