Hi Timo, well distal taper is always good in a blade, Helps stop it snapping under duress, after all.
They should be differntialy hardend if for use but the very tips are likely to be left soft judging from kukri, {Ive never etched a kora/khonra etc.}
if you can lightly etch it you will see whether the man who made it , made for it to be potentialy used or purely a wallhanger.Post ww2 does seem likely, I agree.
Who it was made for, as with many ethnographic weapons from that area we will probably never know. Beheading buffalo is there main job today if made for locals.
Spiral