I find myself wondering if these could be the mysterious "elbow knives" of baguazhang.
The test would be how well you can hold them reversed, so that back of the blade lies along your forearm with the edge out, and it's fairly easy to flip back and forth. If they aren't comfortable that way, they aren't elbow knives.
While a few
bagua practitioners use them, no one has seen a verified, genuine pair. There have been questions about whether elbow knives are hudiedao, simple guardless knives, or something else.
Best,
F