This rare iron tool finely inlaid with strips of copper was designed to scrape along a long metal rod to make tiny metal shavings or particles. The scraping would be done over an altar or perhaps a torma offerings as a form of additional offering, or the scapings would be mixed with a dough or clay to make tsa-tsa votive tablets.
Such a tool was known as a rinchen serder (‘precious golden file’).
The example here has a skull-like face at one end and a finial at the other engraved with leafy flourishes. It is fine condition.
Henss, M., Buddhist Ritual Art of Tibet: A Handbook on Ceremonial Objects and Ritual Furnishings in the Tibetan Temple, Arnoldsche, 2020.