It is a fact these days that such blades are pouring out of Sanaa. Enough said about that and the escapades of the Sanaa boys to remove the rhino hilts and replace with backyard workshop basic hilts simply to raise the price allowing souk owners to purchase swords they can immediately put up for sale rather than just blades.
I have several of these straight variants and clearly bending to curved blade format was an option... I doubt they were originally produced curved but maybe they were.
Having said that, I see no reason why such a blade or sword would somehow reduce in actual collector value since they have had a very interesting history... German blade technology on the African trade blade circuit specific to Ethiopia and hilted with Rhino ~they were good weapons !... Then sent to Yemen and the famous bazarre of Sanaa...and all its incredible atmosphere and history ... There; rehilted and off up the trade route to exotic climes... Salalah and Muscat where they traded to world wide clients ... These were fighting blades in all their glory and recent history ~ On the waist of the occasional Bedu tribesman with blade bending, re hilting et al...
And by the way ... on their travels they almost got written up as fairly substantial Yemeni swords in a class of their own ... until the penny dropped here !!
Ibrahiim al Balooshi.