"Over the past 158+ years that the Smith & Wesson gun manufacturing company has been in business, they have diversified & manufactured items other than firearms.
The Blade Saver is one of these "diversification products."
Manufactured from 1923 to 1936, the "blade saver" was a device for holding safety razor blades so that they can be sharpened like straight razors. There were three types made, one for a single edge blade and two for the double edge blade. Just above the pin that locks the two-halves together, is stamped I, II or III identifying the three types."
Got that from here:
Smith & Wesson Blade Saver | Collectors Weekly