[Jim McDougall]

Wonderful grouping!! These are excellent examples of these sa'if of the Arab sphere. It is important to note that this does not mean 'Arabian' as in Arabia proper, but in the places where Arabs populate the regions, not meaning to get into ethnic discussion.
By the same token, the Moroccan example has long been known colloquially as a 'nimcha', by collectors, but overall, these are all simply termed sa'if.

These are likely 19th century but could be earlier, especially the one you note as Yemeni, which is actually more to the Hadhramaut regions (as described in Elgood, "Arms & Armour of Arabia".

The example with extended crossguard ring has also been somehow classified in collectors circles as 'zanzibari', however in Buttin (1933) these are noted as Arab sa'if, with no mention of Zanzibar. Naturally these were present there, but by no means were they exclusively from there. It seems this classification appeared in a number of references in 1980s.

The blades on these are invariably trade blades, German of course, and the blades are typically early 19th c. These were most typically acquired from Bedouin traders by armorers mounting blades into hilts in locations often in Yemen. With the Moroccan examples (which were often Algerian as well) these were mounted with trade blades, and armorers often added the 'sickle marks' approximating the so called 'Genoan' marks.

The straight blade on the 'Zanzibar' example is of a type of trade blade usually into Ethiopia late 19th c. which usually ended up traded into Yemeni markets. These were often mounted in Yemen on silver hilts of a different form. Ethiopian swords often went into Arabia as the Arabs were after the rhino horn typically on the Ethiopian shotels for their kahdjhar daggers.

In rereading this thread, I just wanted to say that the work done by Ibrahiim al Balooshi (Peter Hudson) here in examining these forms was brilliant! I learned a great deal from his research and contributions.