Incredibly interesting item Tim!
The heavy wood scabbard actually looks very much like a gun stock as found on these heavy rifles, at least to me (not saying that its made out of one, but seems to be emulating that look, as also evidenced by the vestigial trigger presumed). This looks to be an ersatz, probably blacksmith produced machete type weapon, and as suggested most likely from German regions of Africa. One wonders if the weapon was produced to simulate a gun while being carried as a psychological ploy. We know that in African tribal weapons, the imagery is often a key element as seen in the often bizarre designs seen on blades and various elements such as throwing knives etc.
It would seem that German colonial regions in east central Africa or even more southern regions of Dutch colonial posture are most likely for this weapon, which seems of reasonably modern date. Concerning the blade, the exaggerated clipped point/yelman recalls of course the rather dramatic blades we have seen on certain Indian tulwars and even those of the Chinese oxtails brought back from China during the Boxer Rebellion period. Naturally the German presence in China during that time was well established. Either of these influences may have inspired the unusual profile of the blade, and while German trophy might have been the source, so might an early tulwar from the many workers from India who imigrated to these regions of Africa.
Most curious is the inscribed marking near the blade peak at the back which looks like a simplistic and exaggerated trisula, but whether intended as a marking (or the patterning guidelines for the maker) is unclear.
What is the weapon illustrated just above this one ? That too has a pretty interesting scabbard, and the beaked hilt is unusual. Looks like latter 19th century Mexican knives from Northern Mexico.
Just observations and speculation as usual
and looking forward to other comments.
All best regards,
Jim
P.S. My first inclination was to classify this a Zambezian flyssa
and it does recall the macho custom weaponry of Hollywood i.e. "King Solomons Mines; Michael Douglas "Jewel of the Nile" etc.