You are all correct, of course, to note the more ancient penetrations of Caucasian weapon traditions into Central Asia. The old Uzbeki swords are very reminescent of Shashkas, but there is a crucial difference: the "eared" pommels appear later in the development. This was, most likely, the most direct influence of the Caucasian Shashka (in it's Russian Imperial Cossack mutation) on the Central Asian swords. That's what I was talking about and these are the examples I showed. Lebedynsky calls them Pseudo-shashkas not for nothing!
I would love to get my hands on a really old Uzbeki sword, both in it's Shamshir and Shashka -like varieties, but to call them rare would be an understatement of the century: most were destroyed by the Russians when they occupied Central Asia first in the 1860-70s and when they suppressed the nationalist Basmach movement in the 1920s.