Hi,
Allow me to enter this discussion with a "small" delay. First of all, this is ordinary dagger, but interesting one - I consider it nice. Congratulations.
Just idea:
I think it could be part of collection of cold weapons which are/were used within the territory inhabited by Tuaregs (and I am not sure it is common type in western Sahel
). If we are sure, that Tuaregs only used nice arm daggers and belt daggers with brass handles, then we could apply Colinīs parable with Zulu and south African spears, but is it really so ? (If anybody has something like typology of daggers used within different Tuareg confederations /I mean in past/ I would like to go through it, this is what interests me a lot). I personally consider this as one of the types.
I feel for you, Iain, as far as generalisation of Takouba is concerned and also concerning those Nupe brass arm daggers often described as Tuareg daggers. On the other side, it is easy to make opposite mistake (to refuse what is not very typical or well known).
Depply down in Sahel one could find "like Nuba arm daggers" in eastern part, "like Tebbu daggers" you can find e.g.till mid of Nigeria (maybe proliferation of type through Fulani), in western Sahel another type (tassel on the sheath or Mandingo style decor). Maybe I am wrong but I think especially the handle of the dagger presented here is already a little bit more typical for Sahara, than for Sahel.
Territory inhabited by Tuaregs is relatively big. Some sources gives 7 main confederations, some old sources from 19 century 5 confederations: Azjer conf., Ahaggar conf., Air (Kel Ovi) conf., Auellimid conf. and Ar Rerf Ahnet conf. Each of this confederation has (or had ?)several main (aristocratic) "families", if I understan it well. Eg. Azjer had Imanan "family", Oraghen "family", Imanghasaten "family", Izhaban "family" and Ihadhanaren "family". And under each of this families served a relatively big number of subordinated clans (which often vere mixed with another ethnic groups, but I think they consider themselves Tuaregs too, although they vere not allowed to use the whole steel allarh etc.). Some sources speak about West and East Tuaregs, some about North and South Tuaregs. I am of the opinion (but I emphasize this is only my opinion), that it would be strange if there would not be at least any special marks or signs on arms, signs which would differ e. g. north of the total territory (Tuareg territory began on southern Tunisian border in past, i. e. it was under influence of other "settled" Berbers and Arabs) from the south (where Tuareg clans practically lived next door to Hausa/Fulani Kingdoms). Or maybe they used daggers of slightly different design ? Another example: Old Tuaregs in Libya still differentiates styles of turbans in each confederation. I am enclosing pictures of daggers which I posted here already before - there is certain simmilarity in handles. They all were bought from Tuaregs in the middle of Sahara and on Tuareg territory (Ghat and Oubari), nevertheless those people allegedly came from Air.
Regards,
Martin