The Terrace of Light is where the Sha'tar, including A'dal, and Khadgar reside. It was once heavily defended by the Aldor, but now it is defended by the city's newest faction who has taken up residence in the Terrace of Light, the Shattered Sun Offensive. A naaru NPC here will take Heroic Mode instance tokens in exchange for epic items.
The Aldor and Scryers factions each have a bank that contains the faction's quartermaster and their shoulder slot enchant vendor in the Terrace of Light. Allegiance to one faction will result in the loss of access to the other's bank.
The flight point for the city is in the neutral section of the city. There is not an auction house for either faction in Shattrath City, nor are there any class trainers.