Hi,
As for the "inlaid metal decoration", it can also be found on the handles of Hausa daggers (Nigerian Sahel). I believe that Hausa daggers decorated in this way have appeared on the Internet (e.g. eBay) during the last few years (I don't want to speculate if it's old original element or innovation ...). We can see the example in the picture of the gallery
http://www.memoire-africaine.com/armes2.html where (in my opinion) it is incorrectly marked as Kuba (the shape of the handle, the blade, the engraving on the blade and the scabbard are typical for Hausa).
Best,
Martin