Mystery tool

[Jameshow]

A chap at our men's shed brought in this tool?

Tufnol handle and stainless blade bunt with relief channel??

 

[adidat]

Could do with some more/better pictures. Bur looks like a converted sword or bayonet...
Adidat

 

[Cozzer]

Cheese plunger/inspector?

 

[Jameshow]

 

[niall Y]

Could it possibly be for putting a folded edge on thin metal or even cardboard/ plastic/leather? Perhaps, one pushes the material up to the upstand on the edge of the blade and scores with some blunt edged knife or roller along the groove.