The paper's introduction actually does explain it:

In his book, Shadows in the Sun, Davis (1998: 20) recounts what is now arguably one of the most popular ethnographic accounts of all time:
“There is a well known account of an old Inuit man who refused to move into a settlement. Over the objections of his family, he made plans to stay on the ice. To stop him, they took away all of his tools. So in the midst of a winter gale, he stepped out of their igloo, defecated, and honed the feces into a frozen blade, which he sharpened with a spray of saliva. With the knife he killed a dog. Using its rib cage as a sled and its hide to harness another dog, he disappeared into the darkness.”

There's also the story of Danish explorer Peter Freuchen, who claims to have used his own frozen shit to make a chisel to dig himself out of some ice. The paper takes the time to say that it is strictly about knives, though, not chisels