Isn't that the point of using a weapon in the first place? As an extension of your own abilities? If she hadn't won (using a prototype in the first battle) then I think there *might* have been a case for being weak, but then again, by the same token it *was* a Prototype. If anything, the Climatact says Ussop has complimented her (with a brilliant idea) and improved upon, thus enabling her to be able to take on Kalifa later on, regardless of if Kalifa was the weakest or not.