Khyber knife?

[kronckew]

Originally Posted by Saracen

Yes), and at the bottom right in the photo is the bolt with which this khyber knife was attached to the wall)

? - Bolt Looks a bit big for the hole

I'd go for the Russian museum theory. The lack of a T-spine is unusual, never seen one like that before. Grip looks a bit chunky & odd near the pommel end too. Museum replica from a picture? Looks more like a largish pesh kabz (which also usually had a T-Spine), also a 'khyber' area knife/sword.

More dimensions/weight would help, blade thickness at the grip and near the tip (ie. is it distal tapered), is it sharp? Full exposed tang or hidden tang, end peened? Shame there is no scabbard, it helps define it.

(I believe they were T-spined because the blades were fairly thin, and generally not the best steel. It added rigidity and allowed for a thinner, finer edge angle for slicing rather than stabbing.) See also What is a Khyber Knife

Mine for example. A more typical one. Note the very slight S recurve to the spine, one reason they are considered by some to be Salawar Yataghans. 22 in. blade, 5.5 in. grip:

[Saracen]

Originally Posted by kronckew

? - Bolt Looks a bit big for the hole

This is not a problem for Soviet workers in provincial museums.
I like Ren Ren's idea too, but reusing old blades is not a rare thing.

[Ren Ren]

Thank you Saracen! These are interesting examples.