Feather blade

My last five shaves with a feather. I have been the blade every time after the first pass because they Musta had a bad pack. Every shave is rough even if I cork and palm strop the blade. 

I have never received so many duds in a pack from Feather but hopefully it’s just this pack. I bought three or four packs at Whole Foods and I hope I’m not throwing away 20 blades the same way.

It's a myth as ALL razor blades are sharp and as they are aligned in a razor at a fixed distance the blade does not rear and "bite" you.  

While it is true that razor blades are sharper than a utility knife or a chefs knife, that does not necessarily mean that all razor blades will be sharp enoug to shave someone with a coarse beard. In my experience with my tough beard, there are many blades that are not sharp enough to slice through my beard hairs. Some blades cut part way through my beard hairs and then rip them out of my skin. That is a most painful experience. That situation gets even worse if I have several days of beard growth.

If you have a fine beard, then it may be that even the least sharp of razor blades will be sharp enough. I have tried a couple of dozen different brands of blades. About 1/4 of the blades I have tried are not sharp enough for my beard. They include such blades as Derby Extra, Merkur, Gillette Ruby Plus, Shark Super Chrome, and even Astra Superior Platinum, although the later is one of the most popular blades among typical shavers. I have yet to get a decent shave from a Astra SP blade. Even Personna Comfort Coated Lab Blue blades are too dull for my beard on the 1st shave as the PTFE coating is too thick. Once the coating starts to wear off, the blade becomes significantly sharper.

There is a website called Refined Shave in which the author tested about 50 blades using a Bess Certified sharpness tester. While the method is somewhat controversial, I have found a good correlation between his test results and my own shaving experiences with my tough beard.

Feather blades are the sharpest "out of the wrapper", but that does not make them the best in every situation. Because the edge is so sharp/thin, it tends to deteriorate rapidly. I can only get to good shaves from Feather blades before they become harsh on my sensitive skin.

Various razors are designed with differing blade gaps and blade exposures. Using a super sharp blade in a razor with a large blade gap and significant blade exposure can lead to irritation and even nicks and cuts if the shave angle is not correct for the razor and more than minimal shave pressure is used. I would never used a Feather blade in an aggressive Muhle R41 razor, but I can use that razor with a less sharp blade such as the 7 O'Clock Sharpedge Yellow. However, I love super sharp blades in less aggressive razors.
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Yes, blades are likely the most subjective of all shaving kit.  Blades I like and that work well for me don’t get any love from my family members (sharing half my genetics).  And some blades I really like also are on my sons favorite list.  For example, he loves feather and I’m just Ho-Hum about them.  We both like the “sharp” but I dislike the longevity.  I love Personna comfort coated and he doesn’t like them at all.  We both agree that Nacet is a fine blade.  Neither of us find any difference with one blade in particular razors
Why the difference?  Shoot, I’ve thought of that a lot.  Seems for me that my silver whiskers demand the sharper blades but his beard is still supple and colored but he still needs the sharper blades. Is it technique? Sure, that has to have an affect. Some of us have a very light touch and others a bit heavier. Differences in beards? Sure, we know silver whiskers are tougher to cut and of course beard hair comes in all sorts of diameters. Differences in blade dimension?  I’d sure assume so. Although I’ve never taken calipers to blades I can’t imagine there is not some variation between brands or even between lots. Differences in skin? Shoot yes.  My hide is leather and my son has sensitive skin that is prone to razor burn.  
So long and short, yes, blade choice is super subjective.

It seems it is impossible to convince people that what they deem as "sharpness" is not what imparts smoothness in a shave no matter how much objective science one posts up to & including Gillette & Personna explanations in their very patents.

It seems it is impossible to convince people that what they deem as "sharpness" is not what imparts smoothness in a shave no matter how much objective science one posts up to & including Gillette & Personna explanations in their very patents.

The research studies done by Gillette and Personna were back in the late 1950s, early 1960s when Gillette was coming out with their first silicone coated carbon steel blade (Super Blue) and Personna was introducing the first stainless steel blades. The subjects of those studies would likely have been the primary target customer base of those companies:  American caucasian men ranging in age from 20 - 45 years. It might very well have been the case that most men of that age could tell the difference in blade smoothness while considering blade sharpness to be less important. However, when you widen the audience to men of all ages, races, nationalities, skin and beard types, the results are likely to be different. Gillette and Personna were trying to make a case to support their patents for coated blades and designed the conditions of their research trials to prove their point. In a subjective study, it is easy to skew the results to fit your hypothesis.

I do agree with you that "sharpness" and "smoothness" are not the same thing, but I know from personal experience that some blades are both sharp and smooth, some blades are sharp, but not necessarily smooth;  some blades are less sharp, yet fairly smooth. Unfortunately, I did not find Shark Super Chrome blades to be either sharp enough for my face nor  smooth enough for my skin. They were a total fail for me.

I find the same thing when honing straight razor blades. If I hone a blade to the 8K level it will not be sharp enough for my beard, although many people have no issue with 8K edges. If I finish the blade on a Naniwa 12K synthetic, the blade is sharp enough to slice my beard, but it feels quite harsh on my face (it is not smooth enough). If I take that 12K edge and polish it with 0.5, 0.25, and 0.1 micron ultra fine abrasives, it becomes both sharp and smooth. When DE blade manufacturers produce their blades, there are many things they can do to alter the sharpness and smoothness of their products. Because they are selling to a worldwide customer base, they need products that are suitable for a wide range of customers.

I also had same experience of tonylasaraci. I had two box of feather from different sources and test them on more than 6 razor but it was not sharp at all for me and compare to gillette platinum, personna red and gillette 7 o'clock black, it was dull(ymmv). Maybe the wuality changed, who knows!