I will address both Don Gwinn and hso in this missive, no flaming intended.
D-2 is a high Carbon , High Chrominum, World War 1 era die steel.
It is, because of it's high Chromium content rust resistant to a degree approaching that of the 400 Series of stainless steel.
As a matter of fact, D-2 being air hardening, and the 400 series martinsitic stainless steels , are similiar enough that they can be HARDENED and TEMPERED side by side in the oven.
I did extensive reasearch work with a local company that wanted to break into the cutlery line.
D-2 came out smelling like a rose in the tests but the company chose to use 154-CM(ATS-34) in their blades because of it's high tensile strength and its resistance to corrosion(housewife, dishwasher type).
Getting back to D-2.
There is nothing, and I repeat, nothing that will test the edge holding ability
of a cutting instrument more than PAPER namley cardboard.
This is because, paper, being mostly recycled has a high insidence of stuff in it , mainly glass.
In my toolmaking days(now retired) I have had to construct tooling to do a variety of things. Where paper was involved, D-2 was the material of choice.
Try this.
Slice thru the end of a cardboard box repetedly and you will soon feel your knife getting dull.
Correct me if I'm wrong but I think that D-2 blades are available only from custom makers.
Just a wee bit of care will keep any Carbon steel blade rust free.
Respectfully, Zeke