[Jim McDougall]

Good points guys, estimating weapons from various depictions, whether art or in the scope of photography from its historical standpoint, is sketchy.
The weapons being worn or held by the subject often, if not typically, were not likely owned or used by them.

I agree the nature of this image certainly does not look like it is of the period suggested, which would have been likely late 18th c. at best. ...and most obviously not a photo, or even an artistic rendering as it does not seem characteristic of the styles then.

This is rather like trying to gauge the style of sword used by Blackbeard or other sundry pirates shown in period woodcut images in the book by Johnson(1724). The swords in these images suggest certain styles of swords presumed in use by these pirates, but often with somewhat fanciful depictions of 'scimitar' type blades.

This does not diminish the desire to better estimate what type of weapons would have been used by this important female pirate, but such details would be better served by looking into the weapons used by the various groups of Chinese martial artists and 'river pirates' of late 18th century.

Quite possibly such weapons would have been the 'double' swords or knives termed these days as hudeidao (butterfly knives) which were halved to fit into same scabbard. While considered a 19th century weapon, these were noted in accounts of c.1820s suggesting they had already been in use for some time.
These seem to have been an innovation of Southern Chinese martial arts such as 'Wing Chun' and the Cantonese term for these appears to have been 'wu dip do', as far as I have found.

The 'double sword' concept extended to full length swords such as the jian as well, however these were dual weapons held in separate compartments in a single scabbard. The concept of course was fighting with two weapons, much as in the west in rapier duels with either sword and dagger or two rapiers (known as a 'case').

The best study of these weapons was compiled by Gavin Nugent some years ago, noting the rather clouded character of these recorded historically and that they were popularized in mid to later 19th c.
Perhaps the most reliable presumption of what type weapon would have been used by these pirates in China would have been the more well known daos etc. of the period.