Hi Willem,
I am not so familiar with PNG things, however I like it very much.
Have you been to the Tropenmuseum with their incredible PNG collection?
There they are showing also a few tools and weapons.
At the commentation on those tools and weapons, I read that they didn't use metal. Only wood and bone.
So if it is a PNG handle, I don't think the blade is.

Maybe on latter period they did use metal blades by import?
Maurice