Upon reaching level 9, Aion's Mage gets to chose between the Spiritmaster pet class or the Sorcerer, the massively-multiplayer RPG's glass cannon.
In RPG parlance, a glass cannon is basically a wizard, outputting tremendous damage while wearing the least-protective armour the game has to offer. The sorcerer in Aion is meant to stay behind everyone else, blasting away with high damage spells while the big guys encased in metal armour keep them from getting pounded into a puddle of cloth and goo.
I've played the class to level 11 so far, and they're everything you'd expect. If you're comfortable playing a World of Warcraft mage, this is probably your Aion class.