Language: Mandarin Chinese
Source: Classical literature
Description
Dāobǎ shù (刀把束) literally means "handle loop". It is the ferrule, the metal fitting 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
An alternative word used is bǎ gū (靶箍) or "handle loop".2
For a complete overview, see: A Chinese saber glossary.

A Chinese saber ferrule of the round style. Late 18th / early 19th century.
References
1. Tongwen Guanghui Quanshu (同文廣彙全書) or "Enlarged and complete dictionary" of 1704. A Qing imperial dictionary in Chinese and Manchu, each entry double checked and approved by the Kangxi emperor.
2. Qinding Gongbu Junqi Zeli (欽定工部軍器則例) or "Imperial regulations and precedents on weapons and military equipment by the Ministry of Public Works", 1813. Chapter 36.