Just give war an ability that raises parry by a ton and an ability that reduces the next hit by 25% with a decent cd and call it a day. The most broken tanking mechanic i've ever seen was tank pally with that bubble they can put on every other moment and utsusemi and looking into weaker mechanics that are similar is a good place to start.
I think the fact that this job was was probably a DPS with tanking parts is part of the problem and will always be unless rethought from the ground up--no more after thoughts.