I believe this is a recently made (or cobbled-together) sword.
Although it is difficult to glean much from the photos, the blade appears to be well made and may be older than the handle, scabbard and baldric. However, it is a common style still manufactured in modern Aranyik, and I would estimate it to be no older than second half of the 20th century.
The "pommel" plug is something I've never seen before and, frankly, strikes me as a meaningless addition. Some previous owner did not like the look of the typical hole/concavity at the distal end of the handle, and decided it needed to be plugged. As Philip notes, it makes no sense whatsoever.
The handle is either a replacement, or has otherwise been altered. The stonework was either done to increase the item's "curb appeal", or a prior owner decorated it for his own pleasure. I have owned several daab and dha decorated with semi-precious stones (low-grade rubies and, in one case, peridots), but never the type seen here.
Finally, I would not really consider this to be a "Montagnard" sword. Could it have been made for or used by a member of that group of "hill tribes"? Certainly. However, this is a Thai blade, similar in style to the ubiquitous swords brought back with US servicemen from the Vietnam War, as mentioned by Philip.
Thank you for sharing this with us.
