Skill Speed is a pretty bad stat for tanks, especially Paladins. Paladins can run out of TP really fast.

I went with the Weathered Noct Lorica for my first purchase, since:

1. On top of VIT gains, it's a +4 gain in Parry, and trading off 24 Determination for 26 Accuracy from the Valor Surcoat, which was the 2.1 BiS for Paladin. This is also a +14 gain in Parry, in exchange for -8 Accuracy from the Heavy Allagan Arrmor, but given your Paladin is getting a +26 Accuracy, this should put you at close to 500 Accuracy for now. The minimum accuracy required for The Second Coil of Bahamut - Turn 1 seems to be 490 for tanks, so that's a good base line to work towards.
2. If you feel you have too much accuracy using the 2.1 BiS, except the Valor Surcoat being swapped with the Weathered Noct Lorica, you can replace your Allagan Bracelets of Fending for Hero's Bracelet of Fending for an extra +5 Parry and +11 Skill Speed, in exchange for a loss of 16 Accuracy.

Another good option if you don't know if you should spend on the shield is the Weathered Noct Ring, which is a direct upgrade to the Hero's Ring of Fending. Otherwise, you can also use it with your Hero's Ring of Fending for extra Accuracy.

As a shield, the hoplon style shields are good for blocking attacks more often. This allows you to use more Shield Swipes, and have a more constant damage mitigation, although it mitigates for less.