Athanase,
I think Ausjulius is on the right track. The scabbard made from a single piece of wood is typical of working knives from Vietnam/Laos/Combodia. Sometimes these are surprisingly light weight for their size, presumably reflecting a soft wood that would be easy to carve out. The hilt is hard to see in the seller's pics. The shape of the blade is also of that area, somewhat like a modern Thai
enep. I have several similar knives of village quality that were brought back from Vietnam, Laos, Cambodia by U.S. servicemen in the 1960s. They have been variously described as "Montagnard," "Moi," "hill tribe," etc. Your piece may also be from that era, or perhaps earlier given the brass/bronze work on the hilt.
A MSEA attribution seems consistent with some of the other items for sale at the same time.
I like these well worn pieces--adds character.
Ian