This is obviously nuts, but the pawnshop owner soons sees that there are lots of people who believe in this, and in a conspiracy to hide the truth about the Civil War; it helps that his shop assistant is a conspiracytheorist and flat earther, so he can easily key into this stuff. Soon believers are turning up and offering serious money for the sword, which is referred to as a 'prover' item.
This looks like it's going to be a film about a con - the storyline is a bit like the violin scam, which I think forms the basis of a short story that I can't find at the moment. But it isn't exactly - we've seen the two women receiving the sword, and if it's a con they're not in on it. There are some good scenes, and lots of odd ones that seem to full of menace but nothing happens.
Worth watching, but in a very odd way.
Watched on All4 via smartphone and Chromecast.