Missi, in the USSR after the war, knife production was criticized for the quality of the steel and the variety of products. My grandfather used to say that if you bought a knife with good steel at a hardware store, you should run and buy a lottery ticket before your luck runs out. So people sometimes made their own knives or ordered them from friends who made them themselves or knew someone who did. There were no uniform requirements for which knives were considered weapons and which were not. In other words, virtually any homemade knife could be considered a bladed weapon. Incidentally, German tourist knives from the German Democratic Republic were very popular in the USSR. They were even called GDR finkas.
If you're interested, I have a scanned copy of the article "On the Examination of Bladed Weapons" from 1956, but you need to know Russian to translate it correctly; Google Translate sometimes mistranslates terms, phrases, and abbreviations.
Kolevatov's knife, judging by the photographs, appears to be a homemade knife, practically made on the fly. The blade from a power saw (not a chainsaw) was used as the starting material.
Photos of possible "donors":


Krivonischenko's knife, according to Deyev, was made from a file. This tool was one of the most popular materials for making knives. I'll say right away that, judging by the photographs, at least the handle is homemade.
The Thibault-Brignole knife. Could also have been homemade.
As for Kolevatov's knife? Why isn't it listed in the tent search report or the inventory of belongings? It wasn't present during Yudin's inspection of belongings, and why didn't any of the searchers who inspected the tent and testified remember it? Only Tempalov later remembered it. Slobtsov and Sharavin found the tent and brought some items from the tent as evidence, which, incidentally, was recorded. Just so you understand, testimony given in the record is very difficult to retract. It's the equivalent of sworn testimony in the US. Furthermore, if you contradict the testimony given in the record, you can be fined, or even prosecuted. They didn't provide a precise list of what they brought. Therefore, Kolevatov's knife could have been among the items taken. Therefore, none of those who inspected the tent after Slobtsov and Sharavin saw the knife. They only remembered the knife after the items were already in Ivdel, which is why Yudin didn't see it.
Another possibility, which, incidentally, is indirectly supported by other materials in the criminal case, is that the knife could have been kept "as a souvenir," as happened with Dyatlov's flashlight. But Tempalov pressured the person who took the knife, and it was returned to him. Tempalov took no action on this matter.