A quaint Viking custom had been to compose a poem in honor of one's captor, as opposed to the more modern techniques of lying and/or forgetting.

So Egil had one night in order to write a poem commemorating Erik, and fortunately he had a favorite pipe to help inspire himself: it had lines of a ship as well as an ax. Yes, a doubly useful pipe. Thus Egil wrote the poem, saved his head, and went on to other fine smokes in Iceland, England, and Norway.

You ask about the ax notch in Egil's pipe? True. It saved his life. But that's another story.