There are a lot of videos on YouTube showing how to use the edge on up sharpness tester
https://www.sharpeningsupplies.com/...IRoGCd0E0-EL8kR3g1aQL5CZbsRoCm6cQAvD_BwE

Testing the edge will make it duller, as it it measures the force to cut a tiny steel wire.

What you will find is that new razors are sharper than your knives, because their bevel is at a shallower angle.

They also dull fasters.

That is why hand pushed chisels have a shallow angle and mallet pushed chisels have a steeper angle.

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The man who makes no mistakes does not usually make anything.-- Edward John Phelps