Hello Robert,
what a great addition to your collection. Like you I never before I've seen such a spear before. I have a small hinalung dagger in my collection with the common scabbard and it is more as clear that it could be mounted at a shaft/stem to get a spear but I've never seen such a spear before. What seems interesting to my eyes, your spear seems to be constucted as spear and not optional as dagger/spear since the lower rattan binding cover a part of the iron socket as well the shaft and seems to be the fixation of the spear head byself. Again, congrats to such a great addition to your collection. And this thread show again that this is a awesome forum, you get out in short time not only the exact origin but also the local name of this sort of spear!
Best regards,
Detlef