@LuckystrikedWoW That is a general stat bonus - there is also something you get specific to instanced pvp to reward players for focusing on the proper gear over ilvl min-maxing.
It's all very confusing, since that passive you linked is also in the game.
Bop
P.S., I would highly recommend playing Retribution to climb rating on the ladder. As a level 20, it's just far and away the best class at climbing the ladder solo.
If you have a 2nd or even 3rd who you would be playing with occasionally, then your options open up a lot more.
As it is, you can't queue healers in 2v2 skirmishes :/ This is because at endgame (and at xpoff brackets, for that matter) healers in 2v2 skirmishes had like a 95% win rate against 2x dps teams. So for the sake of players who solo queue as DPS, they decided to make 2v2 skirmishes a damage fest.
So unless you're queueing 3's, you won't be able to play holy paladin.
I would also recommend not playing Protection Paladin. Tank specializations take extra damage in PvP and deal slightly less.