Is this a siraui?

[kai]

the hole in the hilt seems natural to my eyes, I have a Kalasan hilt with a very similar hole at this place.

A pic would be great, Detlef!

This is very unlikely to be a natural defect/malformation: The end of the hollow portion of a horn is a fairly acute and rounded "cone" - here we're looking at the endgrain and such a shallow depression does not make any sense unless there was something inlaid. OTOH, the shape does not seem to be perfectly regular and the whole piece is a rather plain ensemble without extant decorative elements...

Regards,
Kai