@ Mr. Whippy: it is quite robust, thanks!

@ Mike: thanks for the info - I did not know that it is called a hobo knife

I thought it was some 'freak of nature' among pocket knives...

But today did some Google-research and found something similar:
fork style:

fork style and assembling system:

@ Screwtape: I like the styling of the fork too!

@ J-sews: I do not know how old it is. In fact I have never thought about its age before.

I have found it at an old house attic (hose was built circa 1928) about 12 years ago. Unfortunately it bears no inscriptions bur one - letter on the inner side of the fork handle:

Maybe it is a 'B' or Greek 'π' or Russian 'T' - hard to say

@ thebullfrog: thanks!
@ Turnstone: thanks, I have tried to do my best with my cell phone camera!