In admiration to your persuasiveness in this quest for truth here is my humble opinion for what is worth:
It clearly stands out as a crude copy of a Jambyia. That being given and the similarity with the craftsmanship of the solid brass grip "Telek" the Touareg version of the "arm dagger" and the African blades, I would say its belongs to the Touareg or at least to an Islamic black tribe of the Sub-Sahara.
I looked also at the Tirri's book but I would always be careful when considering him for the final verdict. If to consider his book take a look rather at page 54 (# 30) and 56 (# 32A) on the Touareg section instead of the so called Palestinian dagger.
Also the option of a simple "souvenir market" with no blue blood is a solid posibility

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