5160, D2, A2, 52100, CPM M4 just to name a few. I might very well be wrong but Carbon doesn't have to mean rusting is guaranteed or high level of care must be taken. Steels have come a long way since 1095 or whatever from days past.
When I got my Fallkniven U2 I had to get the DC4 as well, because the knife wouldn´t sharpen on a whetstone.