The “enigmatic S” stamp (page 111) found on the both sides of the wooden grips of S14 type I and type II bayonets (also documented on Imperial German Ersatz and S98nA bayonets) is almost certainly the mark of the Stembridge Gun Rental Company of Hollywood, USA.  This company was started by James Stembridge between 1916 and 1920 and gathered up large amounts of surplus militaria, marked them with an “S” stamp, and rented them out  for making Hollywood war movies.