Spied these at the antique store today. Marketing has come a long way in the past few decades. A name like this doesn't instill a ton of confidence or make me want to try them all that much. That said, a very cool old display.
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Here's some information on them
Mystery Edge Razor Blades
and here
Mystery Edge Blades
Looks like they were from Fremont Ohio, and the OP's picture is from after the start of WW-II.
Adding one more link
Popular Mechanics
There's an ad from Google Books, from a 1936 issue of Popular Mechanics.
That's some good Web-fu!
Mark