Don't lock on to bosses unless you're gonna hit it with a ranged attack. Are you using a plunging attack when you jump down? Try two handing your weapon for extra damage after the fall; You're not gonna be able to block that big ol' hammer with a tiny shield anyway! Since you have a busted weapon and can't repair, I'd suggest just starting over. What class and gift did you pick, by the way?

krissy: gonna attempt the abyss first since you've gotten the ring, or were you going to head elsewhere? If you have the DLC, you are able to access the extra content now as well.