Ariel generously sent me the odd blade with the flamboyant prong (thanks!
). I've spent a good bit of time handling and examining it. This is, in my opinion, a Thai weapon.
This thing has significant age. The patina is thick, black and stable. I am convinced this is the blade from a pole-weapon later mounted as a sword. The blade itself has what appears to be a spike tang typical for weapons of the region, along with a steel collar. I wouldn't be suprised if a guard were present at some point in its history. The wooden handle is newer than the blade and collar, and has been hand-fit with an old brass shell casing as a pommel.
The spine is thick at the forte (1/2"), and demonstrates a gradual, even distal taper to the tip. The blade is simple, sturdy and shows signs of differential hardening along the edge within the patina. It is, also, quite blade heavy, with the POB approximately 10" before the handle. The edge is remarkably sharp, with an "apple-seed" geometry. Striking in that there is clear evidence of extensive use and wear, but no real recent signs of sharpening.
Overall, I think this is a serious weapon, albeit with very little ornamentation or decoration. Perfect for lopping off limbs, or fighting from atop an elephant.
I hope to remount it with an appropriate pole.