I previously posted this idea in a thread in the Paladin job forum, but in light of the impending job refinements I feel this perhaps deserves its own thread, and that it may get some more attention here than in the Paladin forum. Forgive me if I've erred in the placement of this thread. Anyway...
Instead of adjusting it as a job ability, why not make Cover a job trait? I see this as a simple way to make Paladin much more useful, or at the very least less of a waste of space.
Due to the lack of information as to the planned adjustment to Cover, I'm going to use how it currently functions for the purposes of my argument.
Cover's base duration is fifteen seconds. Unless whatever you're fighting is using an ability like Hundred Fists, or has exceptionally low delay, this results in at best a couple attacks being blocked. Most of the gear enhancing Cover becomes worthless as well, because it's very difficult to time the ability to coincide with blocking a spell or what have you.
In a perfect world, Paladins would always be the focus of the enemy's attention anyway, which makes Cover very situational. As a result, meriting the duration up seems like a waste when you can shorten the recast timers of abilities like Sentinel, Rampart, and Shield Bash, all of which are much more practical. Cover's apparent uselessness not only affects the ability itself, but essentially wastes space in our group one merit category, where a better effect might take its place.
And so, I propose the following changes: Make Cover a perpetual job trait, and change the group one merit as follows; decreases damage taken while covering an ally. Base of -6% damage taken at level 1, increasing by 1% per level to a maximum of -10% damage taken at level 5. (Whether or not this damage reduction would apply to the overall damage reduction cap of 50% or not is up to your discretion, but I feel it should be an exception to that cap in much the same way that Burtgang and Aegis bypass it.)
I feel this accomplishes several things, ultimately making Paladin marginally more useful. It would render Paladin's inability to quickly generate enmity and maintain the enemy's attention a moot point. It has no impact on Paladin's (positive or negative) offensive capabilities, nor would it affect its ability to solo. It negates the necessitation of a complete overhaul of the enmity system, makes some old equipment much more useful, and adds more variety to Paladin's group one merits.
On the whole, I feel this is a fairly simple, eloquent way to significantly enhance Paladin's usefulness, allowing it to shine a little brighter as the impenetrable wall I feel it is meant to be, without any drastic changes to the job or the game.
Edit: Grammar errors.