I think there are merits to both arguments, because the fact is that Africa is an extremely diverse continent and what is true in one region may not hold in another.
West Africa was populated by an enormous variety of ethnic groups, but with very close commercial and political links. Ethnicity was often a religious or economic designator; for example, Mandinkas, Bambaras, Wangaras, Dyulas, Markas, and so on, stem from the same medieval people but to which exonyms based on those factors have been applied. For example, "Bambara" originally meant Mandinka populations that remained pagan, Wangara and Dyula designated trader Mandinkas in Hausaland and the Atlantic coast respectively, Marka was used in the Early Modern period for Muslims within the Segou Bambara state...
Besides, these groups lived mixed with each other. In a region for example you would have a Mandinka village with Fulanis tending the cattle and Soninke traders and artisans living among them, and they might be visited by trading Wolof marabouts, Papel and Beafada mariners trading from the south, and Euroepans and tangomaos. Any attempt at separating them cleanly is doomed to fail, because they tend to regionally mix culturally. So you see "microregional" styles, but shared by a variety of peoples living there, as opposed to another "microregional" style used by those same peoples but elsewhere. This was a fluid and transitional landscape, without clear breaking zones between a particular local style and the next, but the extremes are obviously different.
In this regard, the point made by our friend Pertinax is relevant. Here it is much more sensible to speak of regional styles rather than make arbitrary attributions. I have written elsewhere about this particular issue regarding the so-called "Mandinka" sabers. Takoubas are another example, being a term so broad temporally and geographically, and morphologically, that it is sort of like saying "arming sword".
However, this isn't necesarily the case everywhere. Indeed, in Central Africa there are more specific cultural ties between weapon shapes and a particular people/s. There are exceptions, but it is more clear cut, owing to the particular ecological and sociological traits of the region.
Regarding the dagger in the OP, the area where it comes from is rather interesting. I link a book chapter giving some context.
https://books.openedition.org/irdeditions/25098