At level 74 in Frost Presence that DK would have been lucky to hit 17k hp...and that's in "tank" gear...dps gear he'd be lucky to hit 14k in Frost.
If you pop fear...DK can either trinket/EMfH/WotF or he can pop lichborne...no matter which one he uses your pally could then Hammer him...he then has to use the other one...or sit there stunned the whole time...if he was UH then he probably does not have Lichborne either...so he gets to trinket/emfh and wotf...if he's smart he will wotf the fear and trinket pally stun...if he's not undead all he can do is trinket/emfh...which is 2min CD...compared to your 30sec CD fear...
During that stun...if you and a holy pally cannot put out enough damage to kill him, he's gonna be damn close.
Keeping abolish up the whole fight isn't a suggestion...it's a necessity.
If you would have done nothing other than keep SW:P on him...and dispelled diseases the whole fight you could have killed him much faster...ya see...since you do not seem to understand what others have been telling you...
Death Strike would have been his only means of self healing other than potions...
By keeping ALL diseases off you his Death Strikes would not have healed him AT ALL...
If he has no healing ... and you have a holy pally healing you...you could literally just stand there and spam SW:P on him and keep smashing Cure Disease and re-applying abolish when it drops.
If he's unholy he would not have blood worms and most likely did not have Rune Tap...he could sacrifice his ghoul for health...but thats more time to summon a new one and not dps'ing you.
Your pally could have FoLx2 you and then Holy Shock the DK every time it's up...keep SoVeng/Corr on DK the whole time ticking away...and titans forbid that DK pop Lichborne against a pally and get Holy Wrath/Exorcism'd in the face for half his health.
You guys might be good...I don't know you so I can't really say that you're bad...but I can say neither of you have any idea how to fight a DK and THAT is why you lost...just to illustrate it for you:
"I'm an Enhancement Shaman and I tried to use Lightning Bolt and Chain Lightning to kill a hunter but he just stood there and killed me in like 4 seconds! WTF whaaa whaaa"
Know your class, know the class you are targetting, and cry when you get stun locked...not when you get outplayed, because I can guarantee the whole fight the DK was thinking "wtf lol this dude aint dispelling my diseases, and that holy pally is a newb rofl...he isn't even trying to burn me down he is just spam healing this SP rofl rofl rofl."
One last tidbit of info...DK's can be silenced and it severely cripples their dps...