Strange dagger ... can someone ID?

[fernando]

This has been a riddle, since i acquired it; seller also ignored how old it is, what it is and where it comes from :confused.
Single edged blade, with 12 cms. ... double edged at point section; with three brass filled holes.
Bone handle, with a heavy load of patina ... a bit damaged and missing the pommel ring (?);but the brass ferrule is still there.
We can see that the handle bone was stuffed with wood to acomodate the tang.
That ring between blade and handle and the filled holes should be a good identifier, but i just don't get it myself.
Any help would be so much welcome.

Fernando

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