I had that happen with a Swedishbayonet that I found rummaging through my Grandfather's basement. I was about 8 years old and in retrospect, this seems unusual, was permitted to keep and wear it whenever I felt like it, provided "I didn't try to sharpen it" or take it when we went to public places. Lacking the correct frog, my Grandfather used an awl to make a hole in an old leather belt for the scabbard stud and I had a rather impressive belt knife. For much of my childhood I would have that bayonet along on many of my adventures, chopping at various bits of wood and generally impressing my friends. In fact, one friend of mine was jealous enough that he had to have one too, and somehow ended up with a brand new Nella C7 bayonet and frog, no doubt liberated from nearby CFB Cornwallis, It was much nicer than my old Swede, but as a woods knife it was dull junk.
At some point the locking stud on mine became lost, but about 10 years later I bought an AG42, a rifle that the bayonet fits perfectly.