These Mystery folders were discussed on the forum several times with various suggestions for their use: To repair carpets, to clean opium pipes etc. They were also attributed to India, Afghanistan, Indo-China and other places in South East Asia. For more details on these knives see:
Folding Asian Knives
I just received an interesting email from Mr. Franco Toscani from Italy. And I am quoting the relevant paragraph of his mail:
”…They are actually a sort of \"pen\" for writing on palm-tree leafes:
with the blade you cat the core of the leafe, in a rectangular flat shape, and with the \"point\" you can write on the leaf. The leaf (fresh) keeps the words and it is not possible, obviously, to cancel. Whes dry the leaf is strong, elastic and thin.
I have seen with my eyes people using this kind of knife both in Sri Lanka and in south of India. But I have found such a knifes also in Burma.
Somebody wrote on a book that they are used for cutting and restoring carpets, but it is absolutely not true…”
The interesting explanation on the use of these knives and the attribution make a lot of sense and I am grateful to Mr. Toscani for his mail.