Hi Iain,
Thank you for the kind words, and it is true I have been intrigued by the weapons of the Sahara and West Africa for some time. I think that you might find the paper "A Nigerian Panoply: Arms and Armour of the Northern Region" by A.D.H. Bivar (abstract can be found online) very helpful. With the cast hilt dagger you have shown there does seem to be compelling suggestion toward the Hausa attribution.
While often weapons may have been intended for ceremonial or perhaps court use, it does not mean that they remained so. If the weapon was removed from that context it may well have been sharpened for everyday wear. Takoubas and other edged weapons are very much regularly worn accoutrements into present times in varying degree in these regions.
I think if you do not already have the book, Christopher Spring's "African Arms and Armour" presents outstanding overview on these topics. The title you have noted I had not heard of, but sounds very promising. It seems most historic references to Africa lean toward either anthropological views or earlier periods. Thus, information on 19th century is always great as it gives good perspective on the period of most of the collected weapons.
"Tribes of the Sahara" by Dr. Lloyd Cabot Briggs (author of the benchmark article on the blades of the takoubas) is a great reference as well.
Thank you again for joining us, and for bringing this interesting example into discussion...as always, learning together!!!
All the best,
Jim