Don't get upset if you can only get the edge to a fair level of sharpness. D2 is an excellent die steel where the included angle is just under ninety degrees, but it is never going to rival some of the more traditional alloys. The great thing about D2 and its claim to fame for the "average" sportsman today is that IT TAKES A VERY UNIMPRESSIVE BUT USABLE EDGE AND KEEPS IT FOREVER. That is compared to some other alloys that require much more attention, will oxidize much more noticably, but can attain a level of sharpness that is truly impressive. Technically speaking it is the inability of the high chromium content to allow the maker, be it a man' s hammer or a machine, to refine the grain structure to the same small size as is obtainable with other steels.
And as far as sharpening goes, D2 does what it does and very high (for knife blades) hardness so I wouldn't mess around with AlO (India). I'd go right to SiC or diamond for stone material. With SiO, don't forget a very low viscosity cutting fluid lile air tool oil / three-in-one / or oil cut with kerosene.