Having used the innate ability, <Crimson-Gift >, Desmond suffered from a degree of fatigue. Still, he didn't have the luxury of taking a break. Barely a second after Desmond believed he had murdered Emerard, chunks of the remaining necrotic mass of bone and flesh began to twist and reform into a new entity.
At that point, it wasn't a matter of regenerative abilities anymore, or if that was still Emerard, Desmond had the feeling that this thing was foreign to all of that. Although he had no basis for his beliefs, Desmond felt that this mutant mass was something similar to one of the necrotic beasts used by that necromancer whose name he no longer remembered.