Origin of this mandau?

[A. G. Maisey]

Jeff, my knowledge of Dyak weaponry is slight, however using "Hornbill & Dragon" as a reference, I'd be inclined to give this mandau as Kayan.

As for Dyaks using synthetics, the old Dyak ways have been gone for a long time, even before the clearing and the palm oil plantations sent them out of the jungles, they were using modern materials to do repairs.