Tim:
I'm skeptical about this one. The picture is very hard to see much detail. It does appear Taiwanese. The straight single-edged blade of uniform width for most of its length is typical of the Paiwan knife/sword. The hilt looks to be a recent version of circular cross section that may have been turned on a lathe and then carved -- can't tell from the pics. The scabbard, however, looks wrong for a Paiwan sword. Typically the Paiwan scabbards are closed on the front and have carved designs, with the snake and human faces being prominent motifs. The open-faced scabbard is seen among other tribal groups, such as the Atayal, but their knives/swords are curved and quite different from the Paiwan versions.
So this one looks to me like a hybrid of Taiwanese tribal styles. The person who could help you best is probably
yuanzhumin -- Nicolas lives in Taiwan and knows as much about these knives and local culture as anyone on this Forum.
Another region that has open-faced scabbards is the Naga area of NE India. I don't think this knife is from there, but the picture is too small and blurred to say much more.
Hope it turns out to be a rare treasure.
Regards,
Ian.