EASE OF SHARPENING Both hardness and grain structure come in to play with the ease of sharpening a steel. The harder a steel is the more difficult it will be to sharpen. The finer the grain structure is the easier it will be to sharpen.
White Steel No.1 is a very hard steel with a very fine grain structure that is moderately easy to sharpen. AUS-10 is on the softer side of Japanese steels, but has a much bigger grain structure and therefore is harder to sharpen than White Steel No.1.