A good friend of mine suggested that I might be interested in reading a few novels by Andrew Vachss. The “Burke” series are about a private investigator who specializes in child abuse cases. The books are not the lightest of reading, as you may expect but they have provided insight into an area that most people would rather pretend did not exist, and evil always thrives in ignorance.
One of Vachss’ characters has what I think was described as a “weft cutter’s ring”. She displays this as a response to an inquiry as to whether she can defend herself. The name indicated that it was worn by weavers as a quick and handy way to cut thread. Curious I searched the internet for an image of such a ring, but was unable to find one. The other day, searching for something different I came across the following item. One of the companies that offers these is the “HandyTwine Knife Company” so I suspect these are intended for use by weavers, among others.
A number of designs are available and most appear to have covered or rounded points so these are not really practical weapons. They are, however, an interesting option to bear in mind if you are involved in gardening, handycrafts or any other job where your hands are occupied and frequently need to cut cordage or similar.