Source: Classical literature
Guye is the Manchu word used to describe the ferrule, the metal band around the top of the handle, just under the guard.
Its function is to keep the grip from splitting and ensure a good fit against the guard.1
For a complete overview, see: A Manchu saber glossary.
A Chinese saber ferrule of the round style. Late 18th / early 19th century.
1. Wuti Qingwen Jian (五體清文鑑) or "Five languages compendium". A Qing imperial dictionary in Manchu, Mongolian, Uighur, Tibetan and Chinese of 1766. Published under the Qianlong emperor.