Divine Aura

The Divine Aura is a bonus that comes with the Collector's Edition of Guild Wars. It only comes with the Collector's Edition; there is no way to "unlock" it, as some believe. The Collector's Edition box specifically states this on the back of the box:

Collector's Exclusive: "Divine Aura"
 * Each character you create manifests the gods' favor with a glowing aura, visible to all.

What the Divine Aura does is creates a sparkle from the hands of a character, color and effect depending on the character's primary profession.
 * The Warrior's Aura is of Balthazar, a flamelike orange sparkle rising from the Warrior's hands.
 * The Ranger's Aura is of Melandru, ethereal green butterflies fluttering from the Ranger's hands.
 * The Monk's Aura is of Dwayna, hands pulsating in blue light with wisps of blue left in the Monk's hands path.
 * The Elementalist's Aura is also of Dwayna, mimicking the Monk's Aura.
 * The Mesmer's Aura is of Lyssa, a pure pink sparkle trailing the quick motions of the Mesmer's hands.
 * The Necromancer's Aura is of Grenth, a green drizzle of sparks destined for the Underworld.

The Divine Aura is attached to the Collector's Edition CD-key. It may NOT be transferred to other accounts and adding a collectors edition key to a normal account will not give you any additional slots, nor will you be given back your original key (so doing so will effectively mean that you lose the 4 slots normally associated with the key.)