For some reason, NPCs can't hurt me. I can take fall damage, fire damage, etc etc but no damage from NPCs. I can't seem to find any cause for this either.
A notable exception is archers - enemy archers can still hurt me. Haven't tested it for spears but I'd assume enemies can still deal all range damage on me.
I have no clue why this happened, I just logged in and suddenly enemies couldn't deal melee damage to me.