3FL
Sorry, but it doesn't look like anything to me except a rather poor attempt at passing off a "known" but unseen logo etch. The mark you show isn't "like" the logo pictured in Johnson, anyway..... Look at the differences. BAD stuff here. Blade spline is too high and the etches just don't match in depth or any other way. Cross grain looks to be suspicious also as far as being an original SS blade.
Bad blade to start with that has been "embellished" by a maker's mark that was NOT used during the period on SS, SA, or any subsequent dagger blade made and used during the TR period.
NORMALLY, I've found that "loose" blades are just that, loose (bogus) blades that were made to sell and mess with collector's minds.
This blade is not authentic (to the TR period anyway).
JMHO......
