Other than shackles being annoying to farm in PvE due to the distance the enemies that can drop them are from a bonfire, what other items actually have such a small drop rate that you would get them faster from PvP? Becuase you sure as hell aren't going to reliably get them through invading. Grinding is boring, but I'd argue that for most covenants, it's way faster than PvP right now, aside from the password option. Well, Sunbro co-op is probably the fastest besides that, but for the rest, I don't see why the drop rate is considered that small, especially when you're actually wearing the appropriate item finding gear. If you want the covenant stuff that badly, just use Hidden Body + Slumbering Dragoncrest + Hornet's Ring to kill most enemies that can't be nuked down quickly enough.