I haven't done much PvP on my DK, but personally i'd be tempted to take some points outta desecreation/night of the dead/dirge and put em in magic suppression/anti magic zone instead. The rest seem'sgood though.
is the spec im using atm, seems to work good, still fresh at arenas, im running with a ret pally aswell and we just did games this morning and went 20 and 0, Still getting used to the strategy used, but basically focus a target and burst, its a really powerful combo is the ret pally knows how to heal when needed, aswell AMZ and AMS i find to help alot when you go against casters, plus 10 second AMS can be very powerful.