Guys that's a brushed metal finish meant to help with food release not grinder marks. There are many smiths who use this to make a mate metal rather than a glossy finish. The sen is used to scrape metal in order to "carve" the face of the knife and give the righ convexity. I doubt these guys use a coarse grinder in the process of making the knives. That is not a german factory. They will use a file to round the choil or back of the knife and the rest is water stones of various grits. I bet Maxim could offer some details about the process that kato shigefusa and other older smiths use to make the knives and swords, or you can check it on youtube.