The Evoker is, simply put, a handgun.  The character puts it to their head and pulls the trigger, but rather than blowing their brains out, they shatter their consciousness, from the fragments of which emerges their Persona.  The main characters in Persona 3 utilize Evokers.  There are indications that the Persona can be summoned without them--the members of Strega actually have to medicate themselves to prevent their own Persona from manifesting and trying to kill them--but it's not really expounded upon.<br/><br/>The symbolic significance of the act is also left mostly to player interpretation, though given the game's themes, particularly a strong focus on despair and the inevitability of death, you can probably assume that there's more to it than just an emo fashion statement and an unsubtle dig at the skyrocketing teen suicide rates in developed Asian countries.