If you have a bard in the party/alliance you can have it sleep the warrior and take the drk (drks having lower vitality and defense and HP) to get it over with quickly. If the Warrior wakes up then the Bard re-sleeps, basically kiting it. Cast slow on the Dark Knight NM as well as an Attack Down, hopefully crippling it. I would suggest a PLD *and* NIN (or War/Nin) in the party. when the Warrior Orc hits Mighty Strikes, the PLD can hit Invincible, getting hate and waiting out Mighty Strikes; the Ninja would mainly tank the Dark Knight NM, since it doesn't take MP or anything and Utsusemi will make Blood Weapon useless.
I would recommend : PLD, NIN, BRD, WHM, BLM, RNG for this fight. Ninja can be replaced by War/Nin if you need to since this *is* AF for Warrior
I killed them two with a friend RDM 56. I am DRK 56 and got the WAR quest (WAR 47). They was pretty easy, no need anyone to tank them (I went as DRK/THF and my friend as RDM/NIN).