Right now, to me, it's about a 6. I can 3 shot with it but it's all over the place.

I don't have waterstar, but if the archtype is anything close to FWC's The Fulcrum (DB), it has plenty of potential to be your go-to pvp weapon. Especially with reinforced/rifled barrel. I've been piling up a few hand cannons in preparation for the December update.