Syd, the Seven Stars have religious significance in Taoism. Peter Dekker has a nice short piece on the Seven Stars
jian on his website at
www.mandarinmansion.com.
The shape of the blade on your sword looks Shan to me. The Shan are mostly in SE Burma and neighboring southern Yunnan. The Shan have Chinese heritage and close relationships with Tai and Lao groups in northern Thailand and Laos and neighboring Yunnan. It would not be surprising to find Tao symbols used by Shan living in or close to southern Yunnan, although I don't recall examples of other swords so marked.