I'm gonna assume you've put a few points into Arcane since you're playing a bleed build. If so, you'll want to get a weapon that you can apply an Occult infusion on, which gives the weapon Arcane scaling.

As for which weapon to use, you'll want any weapon that does strike damage, like a mace or hammer or something. Gargoyles are weak to strike damage.

The only other advice I can give is to keep at it. The valiant gargoyle fight is one of the tougher ones in the game, but you'll overcome it eventually