Boundless Conviction

The extra Holy Power is indicated visually in two indents below the Holy Power bar that we know and love. When a paladin has 5 Holy Power stored and uses 3, the extra 2 points of Holy Power will be shifted from said indents into the default bar.

Gameplay wise, I find that Boundless Conviction grants us a little more leeway in building up holy power - especially so for Retribution Paladins (one can never tell when Art of War will suddenly decide to procc.), introduces more burst potential (a Paladin sitting on 5 HP may cast a 3 HP WoG, followed by Holy Shock, and then another 3HP WoG) and allows us to squeeze a little more use out of talents like Holy Avenger (I've had moments where I've used the last second of HA to stock up on one extra unit of HP). Similarly, the ability interacts well with Pursuit of Justice - when a Paladin sporting the talent has expended 3 units of Holy Power, he'll still have two left in his back pocket - granting him a 30% speed increase via the talent.

Overall, I think that the introduction of Boundless Conviction allows us to be less judicious about using our Holy Power generating abilities and introduces an interesting facet to the Holy Power system.

In Warlords, the description is no longer accurate, given that Seraphim always uses 5 Holy Power.

Removed in Patch 7.0.3.