Paladin, how to address the current issues.
What paladin is facing these days is essentially a two part problem: Paladin is unable to hold hate, due to the absurdly low hate cap in relationship to abyssea; and lack of incentive for others to let paladin tank. While a number of paladin's problems as a job can be written off as player error, there's an undeniable fact that the game mechanics are also worked against the primary tank job right now.
I'm sure such examples have been used time & time again, but with how easily hate caps, within the first quarter of a mob's health, basically any damage-dealer can cap hate. Once they reach the hate cap, they'll bounce hate with anyone else at the hate cap, simply based on the last action: Be it an attack on the monster, the monster attacks them, or basically any action taken. This kind of situation happens constantly, regardless of how much the people in question attempt to generate or control their hate, sadly. It's actually almost independent of the damage-dealing capabilities of the people involved, though the higher output will tank for awhile, until the weaker one reaches the cap as well.
When I bring up player error into this, I refer to the mentality of most paladins as turtles, neglecting their swords in favor of ineffective stats such as defense, vitality, and enmity. "Paladin isn't a damage-dealer" they say...well neither is thief or ninja, but they're still used as "DD tanks". Some of paladin's empyrean armor was actually very well designed as TP gear, loaded with accuracy, attack, haste, and enmity all at the same time. Enmity, in & of itself, is an overrated stat and isn't worth idling, unless it's attached to proper damage-dealing gear, such as the upgraded empyrean feet and body. And this is not a new trend, for paladin has always had access to heavier gear than dragoon, for example. Dragoon has transitioned from a light-armor to a heavy-armor job over the years, but paladin had access to things like the Haubergeon early on. Paladin also has access to a fairly strong, multi-hit critical weapon skill: Vorpal Blade.
Now I, personally, am an Almace Paladin. However, I've personally found that this sword, despite being amazing, does nothing to change the situation as when I was Vorpal-tanking with my Honorbound. Chant du Cygne, despite the name, is a very solid & respectable empyrean weapon skill. It increased my damage output significantly, allowing me to kill faster, but it doesn't change how hate bounces around constantly.
I'd also like to bring up an example from pre-abyssea: Colibri. The infernal pink birds of Aht Urghan, which made keeping hate a feat in & of itself, because of their food and TP-stealing abilities, along with their blatant weakness to piercing. Though most deemed it too much hassle, or simply impossible, I personally proved it possible for a paladin to keep hate on these. Using rapier-class swords for the piercing bonus & damage over time (taking away weapon skills factoring feather tickle), along with proper damage-dealing gear, such as the Haubergeon +1, I was able, in conjunction with my abilities, to hold hate against even great axe warriors on the receiving end of sneak and trick attack from thieves. That is to say: the Thf was SATA'ing the War, not me on Pld/War. Why did I bring up this story, you might ask? Because I see it as an example of how paladin *should* tank.
Alas, I should get back to the point of this: It doesn't matter how hard the paladin tries in abyssea, they can go so far as to out-damage the other people in question (which would never work against the heavier damage-dealing jobs such as warrior, monk, ranger, or dragoon), they'll still end up bouncing hate, because of how low the hate cap is set. One of the first, and most important changes I want to see, is a significant raise of the hate cap. I know people have mentioned giving paladin a higher cap, without giving it to the other jobs, and that might be something to consider, but I'd like to see a dramatic increase in the overall hate caps for everyone, just for starters.
The other point I mentioned at the start, was that other people need incentive to LET paladin tank. Even though paladin can tank better than any other job, with certain migawari-justified situations aside (that spell is an insult by the way, paladin should have a passive trait form of it, or at least a spell of their own, but that is neither here nor there), most people simply don't use them. Why? Because they don't NEED to have a paladin tank it. With all the cruor & atma buffs, even a poor excuse for a white mage can keep a melee job alive without once pulling hate. Monk's the major example, since they have a ton of hit points and counterstance to really augment their damage output, and essentially functions like a huge balloon. Monk will never have the control of a paladin, the fight will always be messier, due to the TP being fed to the monster (monk has subtle blow because it NEEDS it, even with capped subtle blow, a monk will feed monsters a TON of TP, simply because of their low delay & fast attack rate), and lack of defense. The point of the matter though, is that while having a non-tank job "tanking" the monster may be messier, it has no real consequences because it works, and results in faster fights.
What I'm getting at, is that people simply aren't rewarded for having the legitimate tank around. Even though paladin will offer better control of a monster, a lot of people simply aren't interested in that, and only in the end results of how fast they can do it.
As for how to address this issue...I have a few suggestions, but no single suggestion on its own would probably be enough. However, here's just a few ideas:
Crusade - Passive trait, similar to Fencer. Paladin gains a damage dealing bonus, based on their enmity against the current target. Or perhaps based on being the monster's target.
Radiance - Passive trait or spell. Monster gains reduced TP for hitting the paladin, shield blocks reduce monster TP.
Curaja - Paladin needs a stronger cure, perhaps something with a heavy VIT modifier, different from Cure V in that Cure V & VI have low set hate values. Perhaps a set hate value for this which is fairly high in comparison. When you have over three thousand hit points at all times on cruor enhancement, a four-fifty Cure IV simply isn't enough. Perhaps a percentage-based effect, so as to maintain balance outside of abyssea.
Fortitude - Passive trait, guards against severely damaging attacks (see: Migawari: Ichi, Sentinel's scherzo)
Paladin does NOT need enhancements to its defensive abilities. I think a new healing spell is overdue at this point, but the main thing is that we need enhancements / adjustments to our hate-mongering abilities. Cover? I personally don't care, I never saw a need for it.
Though I am not an Aegis-owner myself, I know there's been talk on the matter recently, in regards to a desire to balance against the new Ochain shield. Aegis was amazing at seventy-five, because of its shield blocks. The magic damage taken was nice and consolidated, but truthfully, nothing a mortal paladin couldn't achieve through use of their other gear. With the magian upgrades, the shield has seen only an improvement to the magic damage taken, which was truthfully unnecessary, as the original shield capped this effect together with a proper Shellra V. At the level eighty form, that reduced to a mere Shell IV pairing to cap it, which paladin has access to on their own. This is, like I said, without factoring any other magic damage taken gear. In the level ninety form of Aegis, it reaches forty percent magic damage taken, which could cap magic damage taken together with an empyrean body's damage mitigation, without even having shell up. While there are a couple fights this exact condition would prove useful for (Rani, Empousa), in the grand scheme of things, it amounts to no to real benefit to upgrade an Aegis past its initial form. If you want to enhance the shield's magic defense, you need to add something new to it. Such as occasionally annulling, or even absorbing magic damage taken entirely, or reflecting some of the damage back at the monster (made unblock-able/absorb-able, since a number of foes are able to absorb magic damage of their own element, or during certain phases).
Tl;dr:
Raise the hate cap for everyone, not just Paladin.
Give Paladin some new tools to give other people a reason to let them tank.
Aegis needs something besides MDT-.
I don't mean to offend anyone with this post, only give my thoughts on the matter, as someone who actively plays paladin in abyssea.