[Jim McDougall]

As Iain has noted, this does appear to be a European blade, and the mark is convincingly like those used by Samuel Kull, 1847-60 Solingen, placed at the forte as in European practice ("European Makers of Edged Weapons and Their Marks" Staffan Kinman, 2015, p.48).

However these markings do seem to be locally applied, but what is curious is just 'where' in the North African range this might have been done. We know that these copper filled markings are imitating early European marks of the cross and orb and the standing lion(?) (perhaps the 'perillo' mark from Spain 17th c. which in fact was supposed to be a 'little dog' from a quip by Cervantes noting it). .
However the instances of these marks are from takouba (as Iain noted) and from the blades of two Tuareg chiefs from the Kaocen Revolt (1916-17). These chiefs were from the Air mountains in Niger.

Apparently Henri Lhote (1954) considered the inlaying of copper or brass marks was proof of African application, suggesting he was well aware of the practice.
Briggs (1965) cited his reference, but corrected it by noting that this was of course a European method as well. In fact, copper or brass filled marks (latten) were prevalent throughout Europe in 16th-17th c. .

Briggs (p.81) notes further that with the blade of one of these chiefs swords (with copper filled lion and cross and orb) when viewed under magnification, there were radiating cracks indicating the mark had been stamped without being sufficiently heated, so clearly not at the time of production.

While these blades may well have come into the Sahara in the period of 1860s it is curious why these spurious markings were added to them it would appear so much later (1916). As these were on takouba, it is more curious what these same type markings are doing on kaskara blades.

It seems the Hausa, with their blacksmithing skills, may have been a likely conduit with their positioning from as far west as Sudanese regions, and well into Nigerian regions. While not sure if they might have been the ones doing the markings, perhaps blades so marked from whatever point of entry might have carried the influence into both takouba and kaskara blades through them.
Part of my thinking on that is that curiously the Briggs article, which is on Tuareg sword blades, includes thuluth covered Sudanese kaskara blades, which he identifies as 'Hausa'.

While the marking at the forte on this blade has distinct resemblance to the known Kull markings, it is notably different in the forelegs of the 'fly' being filled in rather than distinguishable. In Ed's study he notes that the Sudanese were apparently intrigued by the 'fly' as a marking symbolizing a warriors agility, so it does seem possible they learned to counterfeit this mark as well.
Whatever the case, it does seem to be as noted an early 20th c. blade, if not earlier, and clearly refurbished numerous times since then, as customary with these swords.