Well DVstack is usually your trinket comb of choice as a DK in PvP because
(i) ap/str is your moneystat
(ii) it reliably syncs, which is important in pvp
you can DVhc/STS too which will sync as well and give you a slightly more powerful burst, but ArP as a stat is rather very poor in PvP
DBW is really bad because it doesnt sync, has ArP and 2/3 of times you`ll get a ****proc, but some casuals have it for PvE anyways and use it for the occasional pvp as well.
As for PvE, well DBW is a rather bad Blood trinket (maybe UH too, cant recall their crit REV) because your Haste scaling as a Blood is really bad. It`s decent enough for Frost, but does suffer from the lack of sync issue a bit (less so than in PvP), especially in longer fights.