I think we all know, that shashka appeared earlier 1936) But when appeared the word "sa-shko" - the big question)
Speaking seriously, the first time the word "sa-shko" referred to in 1860, as the Circassian word.
But an interesting fact. The British spy in the Caucasus - Edmund Spenser, describing the armed indigenous wrote to "sabre," and not "shashka." And this is despite the fact that on the flyleaf of the first volume of his book 1839 edition depicts mountaineer with his shashka on his belt.
Although maybe I was inattentive?
Nevertheless. It is possible that the term "Sa-shko" has the same origin as "kangaroo"
I hope you know the story of the origin of the name))))