WWI M1917 Trench Knife - Scarce 'Extra Knuckle' Variation

M1917 Trench knife has triangular blade, retains 80% blackened finish; comparably nice finish on the metal portion of the hilt as well with just a few light rust spots.   Guard has "U.S. / L.F.&C. / 1917" maker stamp, knuckle guard with pyramid studs, and contoured walnut grip.  Guard has an 'extra' knuckle just below the blade.  Complete with nice condition "JEWELL 1918" marked scabbard.  Very few were made in this style were produced making it one of the more difficult to acquire WWI U.S. edged weapons. $400-$600