Brokk produced a strip of leather and a knife. He wrapped the leather around Loki's mouth. Brokk tried to piece the leather with the tip of the knifeblade.
"It's not working, said Brokk. "My knife isn't cutting you."
"I might have wisely arranged for protection from knifeblades," said Loki modestly. "Just in case the whole you-can't-cut-my-neck ploy did not work. I am afraid no knifeblade can cut me!"