Playing around a bit...
Abyssea
Abyssea is weird, and they kind of fuck you over when you start it! You need Traverser Stones to stay in the other dimension, which is another lost Vana'diel timeline. The NPC produces one stone for you every 20 hours, and you can hold up to three. You can use all three in one go, for a total of 90 minutes in there.
It's basically a big open zone, packed with new stuff. There are 10 quests per area, and you can collect 10 "atma" for some purpose by killing monsters in certain ways, it seems.
Every mob you kill gives exp. and cruor, which can be exchanged for a bunch of stuff. Perle, Aurore and Teal armor sets are purchased with cruor. There are also key items that give you additional effects in Abyssea, such as more time - getting that should probably be everyone's first priority.
It looks like at least one BLU spell come from Abyssea, if not more... Clionids are the weakest enemies there, and use Acrid Stream.
Empyrean Weapons
Empyrean Weapons are probably pretty easy to get - they are simply a fancy name for the final stage of the High DMG track for each weapon type. The thing that makes them "Empyrean" is that the trials to complete them seem to require Abyssea stuff.
Walk of Echoes
Absolute madness right now, as one might expect from a free-for-all Einherjar-like thing.
You can only enter a battlefield once per game-day, and it costs 1000 gil at the Veridical Conflux in Xarcabard (S).
