Comments made to our Dark Souls Wiki
In remastered he appears to be almost immune to the Gravelord Sword. I went and got it at low level and matched into his boss room to murder him with it and I was doing about 10 damage with two-handed swings. I actually got caught in a fireball and died while trying to figure out what was going on. I found this hilarious though - I'm imagining him one day going "I'VE HAD ENOUGH AND I'M NOT GOING TO TAKE IT ANYMORE!"
Ignore this. I tried making another character to double-check and the sword worked fine on him. No idea why the first character was doing such low damage.