I went out and found the auction you refer to.
That is a post-WW2 parts knife made by Utica from left over M1 bayonet parts. The guard is a cut down bayonet lug.
When WW2 ended, all contracts for knives, bayonets, machetes, etc, were canceled. Manufacturers were left holding the bag for THOUSANDS of knives and bayonets. The manufacturers did 1 of 2 things, they either completed the knives themselves and sold them or they sold all the left over parts to a third party who assembled the knives and then sold them, sometimes honestly, sometimes with some, or a lot, of embellishment and lies.
Kutmaster was a brand name for Utica Cutlery. Utica made M1 and M4 bayonets for the M1 Garand rifle, and M3 Knives, used by soldiers who did not carry a bayonet capable weapon (machine guns, bazookas, mortars). They made post-war civilian market knives out of all of them.
If you go to the auction site and search for "Utica Bayonet M1", you'll see several examples. If you leave off the M1 in the search, you'll also see some M4 bayonets.
edit to add - a USMC 1219C2 or USN MK2 leather sheath will work - Kabar's current sheaths, model #s 1211S (black), 1217S, 1218S (USMC sheaths), 1219S, 1220S (USA sheaths) and 1225S (USN) are available from tomarskabars.com for just under $11 plus shipping.
