Regenerator made a weapon from his own tibia

It was a thick piece of pale hardwood. It had been scraped down to something that was almost a blade. He recognized the scratches down the length from crude weapons in Iraq. Someone had dragged the spike across rough stone or concrete to shape it.
Then he registered the thick knob under the handle.
“This is a bone,” he said.
“Yeah,” said St. George.
“Someone slipped your prisoner a leg of lamb when you weren’t looking?”
“It is a human tibia,” said Stealth. “To be precise, it is the prisoner’s left tibia.”

Excerpt From Ex-Communication, pg 383
Peter Clines
https://books.apple.com/us/book/ex-communication/id635706546