Fervor JT: Grants 20% damage and attack bonus when the Paladin has the monsters attention. Paladin auto attacks tend to do little to no damage against hnm because of the way one needs to gear defensively. This bonus would help the paladin deal consistent damage and make up for all the time they lose with non damage abilities to keep hate.
Thwart JA: Job ability that reduces damage taken by 75% but lasts only 4 seconds and the paladin cannot move or attack for the duration.
Netherspikes JA or Spell: An attack used by fomors, cone damage plus bind. change the color of the graphic to white/blue and make the bind effect a flat 5 second duration. Using it would prep a light skillchain, and the 5 second bind would ensure any follow up weaponskills would hit their target. could also be used to buy time if the paladin lost hate control.
Trait that grants more enmity on offensive divine magic and healing.
2 hand greatsword traits and abilities: Would give pld a little more dd potential when he finds himself not being used for tanking. Backup tank + light dd.
Spearhead JA: Sacrifice +15% damage taken for 15% gear haste 5 min duration 5 min cooldown. Enhances the total magic damage (duration) of enlight by 100%
Conviction JT: Converts 50% of Vit to Str and 50% of mnd to Dex. 2 hand only.
Intervention JA: Forces the enemy to attack the pld for the next 5 seconds, reduces enmity. Would be used as a backup tanking tool to buy some time to save a teammate. Only works in close range.
Grace JT: 2 handed weaponskills have a chance to restore 25% of the plds mp
Some whm reforms that would help pld as well:
Cure potency becomes divine magic attack bonus.
Holy, Banish, Comet: scaled to be comparable in damage to black mage top tier spells, however limited by element and higher cooldowns.
This would let pld have some magical sources of damage and enmity, and give a better reason to add cure potency to their sets.
Doing these suggestions would also open up paladin to different sub jobs like sch, sam, etc.