Outstanding, that is...sensational!! illustrations Rick
Great information Fearn, and you are spot on concerning martial artists and security. I found some great information that might give us more insight into the use of these butterfly knives.
In "Chinese Martial Arts Training" , Brian Kennedy and Elizabeth Guo, 2005, pp.137-141, there is interesting discussion on these private security companies from about 1800-1900, who employed martial artists.
Apparantly c.1800, one of the early and most prominant firms was named 'Hau You Biao Ju' (meeting friends guard service) and gained notoriety as it was owned by Li Lian Ying who was interestingly head eunuch of Empress Dowager.
As this service developed, it seems every province had one or more private security companies for personal, residence or convoy protection. It is noted that the 'hu yuan' was a bodyguard for residential service, while the 'zou biao' guarded convoys or goods.
Apparantly in the case of convoys etc. the triangular guidon or pennant of the security company was displayed to warn predators off, or at least ostensibly so.
It seems that much as often was the case of with Masonry, the bonds of brotherhood transcend business or political allegiances, and martial artists of like groups in many cases knew each other and trained together. In many instances the guards would contact potential adversaries in advance to establish guanxi, or diplomatic relations. It would seem these arrangements may have taken interesting turns at times, and perhaps there were instances of intrigue?
In any case, one of the martial arts weapons often used by these martial artists were these types of butterfly knives. In cases where ‘open’ weapons were used (spears, halberds, sabers) the triangular banners were displayed. On more covert matters, ‘secret’ weapons such as batons, chain whips and these types of knives were used, with no banner shown.
According to Thom Richardson in “China and Central Asia” ( paper in “Swords and Hilt Weapons”, ed. M.Coe, 1989, p.182), these type of paired weapons either swords or knives, seem to have come into use at the end of the 17th century. It is noted that most of the collected examples of these were made around the first half on the 19th century.
As noted in earlier post, I have seen examples of these with security firm markings from about 1860’s. These butterfly or paired weapons, along with swords with short, heavy blades were favored in the southern regions in crowded city streets.
It is known that interaction between martial artists and river pirates were relatively commonplace, and pirates were inclined to ‘confiscate’ weapons, along with anything they thought worthwhile, so this would account for instances of their use among them.