In picture #2 if you look at the inside of the loop ( I use this term as the hilt reminds me of loop hilt small swords like the one I have
http://www.merctailor.com/originals.php?original_pk=73 ) you can see a slot that runs the whole length in the middle of it. I believe there is a corresponding slot on the knuckle bar of the hilt and that there was a now missing plate at one time.