The D2 spey blade in my EDCF Queen stockman has rusted. The only thing wet it has cut was an apple a week or two ago. Cut the apple, and wiped dry/clean, no washing etc., same as I always do.
D2 is technically a carbon steel, but with other stuff added so its almost a stainless steel. I’ve never had my carbon blades rust after an apple, they just just patina(or “stain”, what stainless steels don’t do..) a little. I’ve also never had one of my stainless blades rust after an apple… So D2 is half way in between? Resistant enough to not patina, but not resistant enough to not rust? Interesting.