Okay... one last thought. Make that two.
First, the vestigial pockets that
would have housed a by-knife and fork are just that -
vestiges of pockets - another likely indication this was made to hang on a wall, possibly with a surplus blade.
Second, IMO the person who spent nearly $500 on this got hosed. For half the price of a dirk, IMO they bought just that -
half a dirk.
Then again, maybe it was a niche piece for a dedicated dirk collector, for whom $500 was probably money well spent on a one-off, even if made as a decorative piece.
I guess that was three thoughts.