I'd rather see Flash extend the duration of the CoS DoT by 6/3 seconds, and spread the GB DoT to two additional enemies in the vicinity. If you couple that with a general enmity boost, and roll block before Crit, you'd solve a lot of PLD problems:
  • Enmity - by boosting damage output as well as boosting enmity by itself, you'd see PLD suddenly able to compete with the other tanks for hate generation. They'd need to make this a level 51 talent, so as to not skew the balance of 2.0-2.5 content.
  • DPS - spreading DoTs and extending CoS will automatically boost our damage output, especially against multiple enemies (which is where PLD's passive mitigation mechanics excel). It wouldn't put us on a level with DRK or WAR for ST MT DPS, but we'd be a good bit closer.
  • TP Management - to maximize DPS, PLDs would need to be hitting Flash more frequently. If it's still on the GCD, then we will suddenly stop running out of TP, because we won't be spending as much of it, and would be interrupting our TP spending to spend MP on Flash, which would then allow 60 extra TP to regenerate.

FFXIV Paladins aren't WoW Paladins, neither in lore nor in mechanics, so I don't think something like the Paladin seals would fit here.