Got to read a lot of those post about the tank situation during the last month, and after reading those 11 pages I must admit this one is one of the most interesting and constructive.
For me, it feels a bit like some tools have been given to the wrong tank.
Paladin has low dps, good physical mitigation and low raid utility. Dark Knight has ok dps, good magical mitigation and ok raid utility. Warrior has high dps, good overall mitigation if done right and high raid utility. that doesn't look very balanced (and I main war by the way). So yeah, some things would be better changed.
Finding a good balance is difficult so don't blame me too much if my ideas get a little bit too over the top.

Somehow I feel like Warrior should be the one with strong physical mitigation instead of Paladin. I would swap the 10% damage down from Warrior with the 10% STR down from Paladin. put fixed parry rate depending on weapon (0% for sword, 15% for great-sword, 30% for axe) and make parry stat boost parry strength instead (and convert it to block strength for Paladin). and maybe make block work on magical damage.
Maybe also add a magic resistance down debuff to Paladin (like bard song but it should not be able to stack)
Paladin still has low dps, but gets more utility, helping increase healers and magic dps.