definitley a bhutanese 'dossum' or 'doo zum', as noted, the faceted grip shape is a dead giveaway. yours has more of a 'sword' tip to it (swords are 'patang') and thus could be a short 'patang'. they also make these in eastern tibet, near the bhutan border - styles do blurr there a bit, but even the tibetan ones are 'bhutanese style'.
i've one, a bit more dressy:
yours is a bit more utilitarian, i like it. many older ones are made from hairpin laminated steel.
here's a photo of the current king wearing a slightly larger (and much more expensive than ours) one. note he wears it on the right side, the negative is not flipped. it's a rank thing apparently.
another link to another forum where these were discussed. the original poster is a well educated bhutanese...
LINKY
best bits are on page 3.

the other 2 pages are also worth reading.