I'm going out on a limb here, but I think most razor blades are sharp. What seems to separate them in terms of perceived sharpness when shaving is the thickness or stiffness of the blade. Example: most would say Derbys are not sharp and Feathers are sharp. But if you look at the stiffness of the blades the Derby is quite thin and flexible and the Feather is quite stiff. If you put a Derby in a shavette or SE razor you will see it is stiffened by the blade holder and it makes them very sharp. And most SE blades are very thick and stiff and thus very sharp when shaving. Anyone care to comment?