"Stainless steel is the sharpest"
Stainless steel it is especially pure steel. There it is not a rule, but usually it is resistant to corrosion and will not rust (almost at all). But has a different structure and it is softer than steel. For this reason it is not suitable for rough cuts. Best professional knives and garden shears are not made of stainless steel. Cut depends on the material quality that is achieved.