Bloody Bone Plate is dropped by Ferrusk, who's involved in The Good Druids and Slime Sickness side quests.
Description[]
| “ | The warrior who once wore this armor died at the hands of a friend she trusted. The mark of her betrayal remains in the bloodstains that have darkened to brown on the gleaming bone-white armor. The armor functions properly, though it makes the wearer unappealing to look at. | ” |