I just watched the video for the first time in a while, looking at the faint markings again. I'm now pretty sure the date is the 11th of some month in 1758.

The inscription begins with "LE CH_H..." and at the end is "LA TOUR." Perhaps someone who speaks French would have some ideas, or may know of weapons with similar inscriptions?

Someone out there knows something that will greatly assist this research, is it YOU?