So Loki broke through Harald’s CoC and snapped him back to his senses. After that, he was strong enough to outright kill an immortal with a follow-up hit. Keep in mind, we’ve never actually seen Holy Knights get killed before. Garling himself survived Xebec, and was fully healed by the end of arc. By this point, Loki was clearly operating on a level far, far above base Harald lol.