(1) Why wouldnt u have a steel cyclone ready? I always made sure to have one ready for the next pull. (obviously not holding it if its still only the middle of the fight, but when the fights almost over, save it up for the next pull, no point wasting it on only 2 mobs.)
(2) Berserk did insane dmg, with massive threat. (and during pacify time frame, u had flash as filler till pacify wore off) (They also had another DPS buff, i think internal release, or raging strikes, i forget what it was called)
(3) Vengance also added to your threat, along with all the self healing. (Thrill of battle, Second Wind, Blood Bath, and later Equilibrium replacing second wind)
(4) WAR had the ability to nullify the dmg penalty, leading to even more threat.
Depending on patch/expansion, berserk wasnt always up, so you alternated between it for 1 pull, and unchained for the other. (Unless doing super pulls, then they were usually both up)
WAR always had an answer for threat. PLD did not. FoF + circle of scorn was the best they had. and then flash spam, or tabbed RoH.
All tanks are simmilar and practically the same. but even among small differences, one of those small differences is the "bigger" difference. Thats all I was getting at by saying that was the biggest difference. I still seem them as being practically the same. But I will agree I forgot to reply about ultimates like LD.
DRK is the same playstyle.
BS/Fell at 50 gauge, IF you dont have your oGCD 50 gauge spender. Eye/edge for your DPS buff.
otherwise 123.
The core difference is that WARs 2nd gauge isnt a bar showing when the best time to use eye, where as DRK has an easier to read gauge, AND can just oGCD its buff, AND can double up on it. WARs overwrites its own buff, leading to a mess up in the rotation. This is the core reason WAR is "technically" harder. (Otherwise id say they are roughly the same)
Lastly is the other oGCDs that DRK gets to press. These dont functionally have any effort in them, other than, when they shine, press them. WARs only other oGCDs require pressing at correct windows, and not any other time. (but this doesnt mean WAR or DRK are harder in their oGCDs)
Both have AoEs they need to "aim"
The core difference in difficulty between the two tanks, is the minimum play, vs max play. at minimum, DRK never needs TBN, and doesnt have to watch MP. But at maximum play, DRK does need to watch MP.
So DRK is the easier of the two to play for a bad player, since it flows smoother, and doesnt punish as much, but its the harder of the two to play for a good player, since theres more room for min/maxing DRK. (But over all, both are pretty darn close)