I think the rivets have been replaced. Both sides of the grips show that the original rivets had larger heads. Looking closely there is a gap between the rivet and the hole. The domed side also seems to be recessed into the grip. I have included photos of one of my Geco for comparison. That said, I like the TM stamp
Or the grip plates have been replaced but finding some to fit a hilt is difficult. Yes a sharpen blade takes some value away from it, but that can be corrected. A sharping stone can dual a blade and buffing can hide the sharping of most blades.
Or the entire hilt may have been replaced with smaller rivets, which would be the best bet.
So it may have been a Firemans bayonet and now with a replace hilt it is now a Heer bayonet.
Sorry for my rambling thoughts.
