Hi Martin,
I think it is from "Afrikanische Waffen" I do not have the whole book only some scans. But when I saw this sword I was reminded of this page.
Because of the curve in the scabbard it may be possible like Colin said, that scabbard is not original to the sword. I completely agree with you those "bands" on the top of the scabbard feel very Mandingo.
All the best,
Iain