Welcome to the forum! and sorry for the lack of responses here, I think you caught us at nap time
I am curious about the information your friend has on this, claiming it is a M1797 Russian pioneer sword. I checked Wagner ("Cut and Thrust Weapons", 1967) and found the M1827, which is a solid cast brass hilt very much like those of the well known artillery briquettes and frankly is nothing like this one except for the heavy sawback blade.
What is most curious is the wood grip on this which recalls those on bayonets, and the most similar example to this type grip is an Austrian type M1862 pioneer falchion. This however has no other similarities and no sawtooth blade.
The crossguard on your friends example is curious and not familiar to me, though like most everybody else here, I'm not much up on Russian arms.
Also, there is precious little on other ranks weapons of these kinds unfortunately, and in many cases these were pretty much ersatz weapons put together to arm forces during various conflicts by unrecorded firms or contracts.
The markings stamped in the guard and on the blade also are not likely to give a great deal of information as these are usually control or inspection type marks which are no longer recorded or used, especially from those circumstances. The largest production factory later in the 19th c. was Zlatoust (c1817 on) and there were also centers at Sestroretsk, Olonets, Ijevsk as well ("Russian Military Swords, Eugene Mollo, 1969, p.3).
One of the marks appears Cyrillic, which I presume is leading us to Russian provenance.
I used the Mollo book (opcit.) which has almost nothing on other ranks swords, focused mostly on shashkas, and the Wagner book (1967).
Other sources listed are:
"Russkoe Oruzhie XI-XIX vekov", M.M. Denisov, Moscow 1953, which apparently was Wagner's reference for the M1827
"Historical Description of the Uniforms and Armaments of the Russian Army"
by Viskovatov, 30 vols St.Petersburg, 1844-56
I wanted to share these athough probably hard to access. It might be worthwhile to contact the National Army Museum in London as they have good records of Russian arms from the Crimean War (1853-56) and if these are Russian might have been in use.
I would suspect at this point this sword, clearly a pioneer type (the sawback is for clearing and putting together breastworks etc.) is probably an anomaly rather than regulation pattern, and likely mid 19th c. By the 1860s the Russian regulation sidearms for other ranks seemed usually cast brass.
I hope this helps and that maybe others here might be encouraged to check their references as well.
All best regards,
Jim