[Ibrahiim al Balooshi]

ED it is always a possibility that parallel development happened purely accidentally in unrelated tribal regions...however in this case I suspect the opposite reaction...and it is equally possible that the two groups mixed technology from and onto both their weapons. In my view the drift was East West. The Omanis were in big numbers in the Great Lakes and one of the most famous was governor of the Falls entire massive area >>Tippu Tib who not only gathered and transported slaves to Zanzibar but also owned huge spice farms there and owned 10,000 slaves in The Falls region as well>

If I can quote your querries and add to them here;

Mainly, why would the Manding, the inheritors of the high cultures of the Mali Empire, appropriate the culture of the Omanis, or the other way around? Basically, why wouldn't form follow function independently for both groups?

I don't think they did>>>what appears likely is they commandeered sabre trade blades and seeing the Omani Long Hilt placed their own hilt design in similar style making the pointed stiff curved fighting Manding sabre...with a Manding Hilt...and scabbard...with what I believe was a snake head end..The leather artesans were early converts to islam and would have avoided using decorated snake heads since it was forbidden in Islamic art
To this was added the Manding shield...

The Omanis seeing the Manding curved were so impressed they adopted this curved weapon but dressed with a built on Omani Long Hilt and Omani Scabbard....and to this was added the Omani Terrs Shield .

The Omanis were a sea trading power with interests on the East African coast into the Red Sea, Persian Gulf and with India.

Indeed and in moving their capital to Zanzibar the Omanis in about 1830 boosted trade into this HUB a thousand fold! The Falls was a giant magnet propelled by Tippu Tip who dealt in slavery and the Manding did the same thing ~ actually Manding were rounded up and exported en Masse themselves by Manding accounting for the bulk of slaves entering the Americas...I show the curved blades in the drawing to illustrate that curved blades with sharp points were in Zanzibar at the time Churchill was there after Saiid bin Sultan...and as the trade boomed for the Manding. Not only trade in slaves but Rhino skins for shields and horn for hilts...the falls area was full of Rhino at this time...In terms of Indian trade the Zanzibar rulers allowed the Indian merchants a very free hand in their trade options allowing great flexibility for them without much interference...