Most vintage blades will not be as good as modern blades, they offer something more important, namely nostalgia and exclusivity, not to mention bragging rights with friends and family! Do keep in mind that razor blades prior to 1960 were mostly carbon steel, and today's blades are mostly stainless steel, stainless is more resistant to corrosion and wear, and lasts much longer. Expect less shaves with your vintage blade and dry it immediately after use to get the maximum amount of uses out of it. They will more than likely not provide the best of shaves, so enjoy the experience for what it is, something your grandpa endured 70 or 80 years back
Velvet edge razor blades were made in the 40's in the USA, they made double and single edged blades, it is quite surprising to me how many blade manufacturers there were at the time! The brand is not to be confused with Velvet razors, a British brand that made some pretty nice, solid safety razors. Pack not opened, by weight feels like it has 2 blades in it, pretty much the norm at the time with the thicker paper wrappings.
Note* For obvious reasons vintage razor blades are a lot harder (and more expensive) to find than vintage razors, and such items will come and go on our website, grab more than one pack if you could, one to try out and one for your collection, soon enough they may not be available at all!