The name of the game is still mastery
The pieces beyond tend to fall into four priority categories depending on their secondary stat allocation: mastery/avoidance, avoidance/avoidance, mastery/threat, avoidance/threat. In that order. With the second option, you want to reforge one of your avoidance stats (depending on your current balance) to mastery. Likewise, for pieces with threat (i.e., hit or expertise), convert the threat to mastery or the most appropriate avoidance.
Just like at the start of 4.0, the best stat for you will be mastery. This is especially true now that the Holy Shield buff (I'm legally obligated to use the "b" word now!) makes block capping a priority in order to squeeze every delicious drop of mitigation from the change. You'll want to continue to reforge mastery onto every piece, as well as employ mastery-themed gemming and enchanting.
Ideally, block capping will be very likely this tier with all the gobs of new stats that comes with higher iLevels. Initially, you may have to employ some fancy tricks, like dual mastery trinkets or gemming outside of socket bonuses. Keep in mind, however, that you don't want to shoot yourself (and your survivability) in the foot to grab extra mastery when it might be untenable. That said, the loot is on fire!
There's really only one obvious choice here, as the Helm of Blazing Glory (which drops off Baleroc) has that wonderful mastery/avoidance itemization. There's also the Immolation Faceguard, our tier helm, with a less optimal parry/expertise setup. Getting it depends on a token drop from within the Firelands.
Best initial choice is thankfully very easy to get -- the Stoneheart Necklace is available from the valor point vendor for the cool price of 1,250 VP. There's also the (presumably trash drop) Firebound Gorget. The lower iLevel Fireheart Necklace is available after completing the Molten Front quest Through the Gates of Hell.
No mastery/avoidance options here, unfortunately. Our choices are the Spaulders of the Recurring Flame, which drop off Alysrazor in the Firelands, or the Immolation Shoulderguards from a token drop.
While the iLevel 378 Durable Flamewrath Greatcloak is (obviously) a higher iLevel than the i365 Mantle of Patience, the latter is actually a far better choice off the bat because of its magical mastery/avoidance combination. The Greatcloak is available from the Avengers of Hyjal rep vendor at Friendly, while the Mantle is from the Thrall quest chain. So, not only is the Mantle a better option but it's easier to get as well.
You'll probably end up with the Immolation Chestguard as one of your early valor point pickups (cost: 2,200 VP). A fine choice, though shed a small tear for the much better itemized Carapace of Imbibed Flame, which drops from Beth'tilac.
An easy pickup here as well. The best choice is the Girdle of the Indomitable Flame from the Avengers of Hyjal quartermaster for only Honored reputation. The other option is the Uncrushable Belt of Fury, which drops from Shannox in the Firelands.
Multiple options here. The best are the Bracers of the Fiery Path, which drops from Majordomo Staghelm in the Firelands. There's also the Bracers of Regal Force, which is presumably a trash drop. Lastly, you can pick up the Gigantiform Bracers (great name) for 1,250 valor points from the vendor.
Best choice is, happily, the Immolation Handguards from the valor points vendor for 1,650 VP. Then there are the Eternal Elementium Handguards which are craftable by blacksmiths.
The best choice for the leg slot is the Immolation Legguards tier piece, costing 2,200 VP at the vendor. Your second best choice are the Legplates of Frenzied Devotion, which drop off Shannox in the Firelands.
Multiple choices here -- the best choice being the Mirrored Boots, which are crafted by blacksmiths. Following that are the Cracked Obsidian Stompers, which drop from Lord Rhyolith. There's also the i365 option, from Molten Front quests, the Pyrelord Greaves. Even with the expertise, the second choice is definitely better than the third, as it can be reforged to offer more total avoidance.
Woe to us, that we have this horrifically ugly shield foisted upon us. The Shard of Torment is quite possibly the worst looking shield since the Shieldwall of the Breaker from Ulduar/Auriaya. I can consider myself a connoisseur of fine bulwarks, and I must say, and this is a terrible piece of hardware. I look forward to jabbing out the eyes of my enemies with those ghastly horns. Or myself, so I don't have to look at it anymore. Whichever comes first.
Easy choice here, the Mandible of Beth'tilac is obviously superior with a combination of avoidance and mastery, and it drops off the first boss of the Firelands to boot. There's also the Obsidium Cleaver, which looks like a trash drop. At the very least, the Cleaver will be available on the auction house (as it's BOE).
I'm a bit taken aback by some of these trinkets, as they have some of the most unique procs I've seen in a long, long time. The obvious choice for best trinket is the Spidersilk Spindle, with its mastery base and excellent proc. For a second mastery trinket, you can use the (more DPS-oriented) Essence of the Eternal Flame, available from the Avengers of Hyjal at revered. For a mystery/avoidance trinket, you can check out the Stay of Execution, also available from the Avengers of Hyjal at revered. Rounding out the pack are the two stamina trinkets, the Scales of Life (trash drop; BOE) and the Moonwell Phial (i365; from Molten Front quests).
Aside from the religious obligation that we all wear Theck's Emberseal (despite Blizzard slandering the poor guy with a less than optimally itemized ring -- nonetheless, horses and mouths and such), the best two choices are the Adamantine Signet of the Avengers, from the Avengers of Hyjal, and the Deflecting Brimstone Band, sold by the valor point vendor for 1,250 VP.
Because it lacks mastery, the Deathclutch Figurine, is a bit disappointing. Even when reforged, it comes up almost 0.5% short in its i378 incarnation. The i359 Relic of Khaz'goroth is a far better choice for maximizing combat table coverage. Nonetheless, if you're looking to pick the Deathclutch Figurine up, the valor point vendor has it for 700 VP.
The Light and How to Swing It tries to help paladins cope with the dark times brought by Cataclysm. Check out our protection 101 guide and our suggestions for protection paladin addons.