I should probably just leave this area for now and come back. I have two keys that I don't know what they go to so it's not like I don't have other things to do.
I thought you wanted to get that a while ago >_> It does full damage but bounces off shields and bosses, so it's not spammable. Definitely need the 12 faith.
Pretty sure many people encouraged you to explore that path before going through the swamp. Not me though, I'm a meanie. But seriously upping your resistance does nothing if you're constantly poisoned.
Getting hit by leech monsters covers you in leeches which constantly bleed you out until they disappear. Best way is to just equip a torch in your hand for a second, makes them disappear instantly. Torch is found in the shrine shop.