Stuff like Cover was, sadly, an answer to the people in 1.0 who complained that they wanted iconic abilities and jobs in the game. This said, I did suggest a long time ago that Cover could be implemented like
Vigilance from WoW.
As I've repeatedly said, Clemency is an off-tanking skill. It's hybrid off-healing with the appropriate trade-offs. Of course it's not going to be a sure thing while getting hit in the face by the boss; that's an intentional part of the design. It's also eerily similar to how I'd expect RDM off-healing to be implemented.
Divine Veil's cooldown is fair for what it does: mitigate raid damage. That said, this is also a 1.0 relic since it used to provide a HoT on people near you when you received heals, and I'm guessing they thought it was a good mechanic to use. The only issue I have is the cooldown, but knowing that the shielded amount is based on the PLD's, it would probably be too much to reduce the cooldown to something like 90 seconds.