One change you can make is swapping out some of your PVE gear for PVP gear. You will pick up more Strength, Armor Penetration, and in some cases Stamina. Also, the Resilience can be used to replace Defense for the purposes of remaining crit immune. In general, I like to keep the set bonuses from armor, which means I'll use PVP gear to fill the back, neck, foot, trinket, and ring slots as needed. When I do this, I don't lose much Armor or Stamina, but my damage output increases significantly - especially when tanking multiple mobs.
PVP gear is very easy to get because you use Honor points to purchase it. If you don't have enough honor, you can exchange Stone Keeper Shards in Wintergrasp for some quick Honor points. As of the patch, you can now purchase some iLevel 264 pieces!
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