Well, Tim, I guess I better fess up and admit to owning a couple of these. There is an old thread where I posted pictures of a "Kuki dao" -- Rawson attributes these dao to the Kuki people. They coexist with the Naga but are on unfriendly terms with the Naga, historically and even relatively recently.
This is the brief thread from a few years ago:
http://www.vikingsword.com/ubb/Forum1/HTML/000507.html
These are the pictures from that thread:
Ian.