answer:With some practice, you can judge the sharpness of a blade by the way it nicks the ridges on your fingers. Again WITH SOME PRACTICE. if you do that wrong (particularly with a blade that’s much sharper than you think), you’ll give yourself a very clean but nasty cut. The way I was taught to check the sharpness of a chisel after sharpening is to (ISYN) lick some of your arm hair, and shave with the chisel. Arms are a bit more durable than faces, so if you nick yourself it’s not the end of the world.