STD
I'm able to sharpen mine on a plain old Norton Arkansas stone. Just a few strokes and it's touched up. I've never actually had any of my Doziers get truly dull. Bob's D2 holds an edge better than any knife I've ever had. Never a problem with rust either. Not even so much as a stain. Even though D2 isn't a "true" stainless, it's only about a half a percentage point of Cr. away from it. While my Randall's from O-1 will take a stain almost immediately upon making contact with the acids in meat, my Doziers look like brand new after a season of gutting and skinning deer and doing nothing more than wiping it on my pants.