If you are looking for any of these things than you are playing the wrong class. Out of all those things you mentioned the only thing that any spec of dk does is spread diseases and unholy was the only one that really worried about it. Duel wield has always been frosts thing sure you could use a 2 hander but it was never really viable. You could also duel wield on a blood dk in mop but you suffered for doing it. Personally I don't care if frost was 2h or duel wield but AFAIK fury warriors can't xmog their 2 handers into one handers which I think would be easier to accomplish.