The Enhanced Repeater Pistol! May be small but it has a skill that you dont have to reload and can shoot up to 8-9 shots in one stand! Found it while fighting Remmington on Kingshead. I think it had infinite venom shot, although I dont remember; have to check later
Another really good weapon that I like is the Hex Stopper Musket. Makes a hex guard barrier around you while under attack and has infinite hex shot.