Source: Period dictionary
Jeyen means the point of a saber.1
Chinese saber tips come in a variety of shapes, from acute tips to more rounded ones, to oblique tips like common on Japanese swords. some are purely single edged, others have back bevels and yet others are fully double-edged.
A sharp backedge on a 17th century northern officer's saber.
A variety of Chinese saber points.
For a complete overview of saber terminology, see: A Chinese saber glossary.
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.