This style of handle is said to have been used in central Ethiopia, around Addis Ababa. Now I have a link to photo of the application on a kitchen knife that is quite old:
http://www.vikingsword.com/vb/showthread.php?t=13705 . I'll find some more photos tomorrow (hopefully). They are still being made, not as nice as they used to be. Probably mainly for tourists. I can imagine that they are already being delivered around Ethiopia to various places (for tourists). But I don't think it's Konso in origin. A colleague of mine had it as an old family knife - he was coming from central Ethiopia. He was Oromo, but I don't think it was a purely tribal thing. Rather, regional specific production. There are also Amhara people in that part.