The stab wasn't fatal; neither could such a thing kill a Rudolf—much less a King. It's just that their defenses never worked with something that had such a high purity of silver in it. Not only that, but the contact caused immense pain to his humanesque hand. Nicholai even had to morph his arms to deal with the wound, just so he could touch the thing without getting scalded.
"Humans and their little toys…" Nicholai pulled out the knife and threw it at the side, sending the knife deep into the wall. He watched the mother and the son scream and join each other at a farther spot. His voice didn't morph back into its soothing human sound. "Do you know why you're still alive right now? If only my mate didn't wish to spare you…"