I’m doing the exploring lotr blitzkrieg, and am currently listening to volume 99. The “a narrow shave” metaphor interested me, for unknown reasons. Could it be a shave as in when one whittles wood, one produces shavings? A narrow shave is a very thin delicate piece, and is close to the final shape. It would also symbolize the small piece of morgul blade that was “shaved” off into Frodo. Seems to fit.