While there is certainly no way to say a final word in appraisals, especially when dealing with such a poorly researched subject as caucasian weapons, I would argue against the hilt being of recent manufacture.
The niello work is "circassian classic" - lot's of open space, motiffs of earlier type rather than later dagestani version, with zigzag fillings. If we accept the circassian provenance, it is highly unlikely that it is post-1864 (since at this moment circassians almost disappear as a race, not speaking of their complete eclipse as weapon-makers). Niello seems also to be of a quite good quality, I like the way it stands out. I am no expert, but I would suggest 1840's being more or less a good guess.
The blade is probably a trade-blade, very likely initially made in Solingen or so, not necessary specifically for Caucasus. I like this shashka.
Concerning the "sound-testing" of weapons - it's a classic. If you drop a sword with it flat side towards the flow it is any good it is supposed to emit long, very high pitch sound - at least according to the "tradition".
My pseudo-scientific take would be:
a. You want your sword be very flexible, with high elasticily which corresponds to a relatively weak "viscous-style" damping of oscillations, therefore the sword will emit sounds for a long time.
b. You don't want to have extensive coupling to next to uniform and uniform modes, for it is what you expect to have unless you use some super-nonuniform excitation. Obviously is these modes are excited during strike, their will suck the energy and "jerk around" your hand. Therefore you don't want to hear low-pitch sounds.
Now I have a problem, because I would expect that the good thing would be if the sound would be high-pitch and very weak (we simply do not couple to the modes).
P.S. May be they just liked the beatiful sound, no science in mind
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