[Rivkin]

Thank you very much for all the kind words, but I'm way over my head oftering the appraisal here, but:

a. Assuming that the sword is russian - Zlatoust, Tula independent makers are the possibility. The problem is that the signature is clearly in arabic (amal...), but russians used cyrillic or stamps (solingen stamps for germans working in russia, zlatoust stamps for zlatoust). Additionally their work was mainly designed for cossacks, not georgians, so it would be strange to see them making this sabre.
Additionally the produce of Zlatoust was considering vastly inferior to high end georgian makers until very late in XIX century.

b. Attached is a "khevsurian sabre" from Astvatsaturjan's book - as you can see it's almost idential to "mountain sabre" from Askhabov's book so it's no wonder we have all these problems in identification.

c. There are however some things in the motiff that look strange to me:
First of all - given attached three images of istambul-bik - first one is from this sabre, second one is transcauscasian istambul-bik, and the last one on the right is a dagestanian.

It seems that the one from the sabre is more transcaucasian. Zigzag pattern that is placed on the hilt and guard - it's also more of a georgian thing, like one on the shashka's blade (image attached).

Than as you can see - images on the blade have a mesh-like background - does it look similar to the zigzag pattern on the next attached image ? I don't know it looks somewhat similar to me.

Than 8-fold ovals on the hilt - this is certainly something very georgian - appears also on the khevsurian sabre in Astvatsaturjan p.343 (khevsurian sabre). Mjalhista's sun is much bigger and sometimes somewhat elongated in one direction.

Other elements of the ornament (Muchal-bik etc.) are also analogous to Dagestani elements, but different nevertheless.

I strongly suspect the origin of the blade being Tiflis. It's not even impossible that it was ordered by a wealthy Tsova-Tushin or Khevsur, remembering that khevsurian swords signed "Ferrara" used to cost 25 cows and up, this blade does not seem like being much more expensive than that. Some of mountainers acquired considerable wealth as a result of military actions, so it does not seem improbable to me.