[Jim McDougall]

You're right Kubur, this is a fun, and challenging discussion.
I think the case for these spherical pommel, shouldered or flared guard integral with grip swords being Yemeni is of course well known.
However, I don't think that it has been implied that somehow a Bukharen sword was brought back to Yemen, and suddenly all the Yemenis wanted such 'Bukharen' swords.

The point desperately trying to be made here is that this form of hilt was widely adopted THROUGHOUT the Dar al Islam, and examples in Bukhara, as well as through CENTRAL ASIA reflect the same styling.

While many of these examples are indeed Yemeni, they did not hold an exclusive patent on the design, and as often occurs, the influences did apparently diffuse via trade, diplomatic and other channels throughout regions from Arabia, the Middle East and Central Asia.

To reiterate, Bukhara was not the SOURCE of the designs, but ONE of the many regions which in varying degree adopted them.

In "Arts of the Muslim Knight" (ed. Bashir Mohammed) I attach three examples which show the collared hilt and spherical pommels and are identified as Central Asian and from 9th century. These are remarkably similar to the 'Yemeni' examples ; the Auctions Imperial example identified as 19th c. Bukharen; and others.

In "Two Swords from the Foundations of Gibraltar" by David Nicolle, the attached plate (#28) shows a bronze sword as late 10th, early 11th c. from a shipwreck and it is noted to likely be from Armenia or Azerbijian.
In the same article, a sword with remarkably similar style hilt is shown as Roman, 2nd c. AD.

So my question is, is it possible that the styling of these hilts developed from a quite ancient form or group of similar hilt features, became popularly known, and were adopted in numerous cultural spheres ?

So we are not saying that these hilts or affectations come FROM Bukharen influence, only that Central Asia apparently SHARED them, just as Yemen did.