The Spellthief Edit
Spellthieves are practitioners of both arcane magic and skills of subterfuge, stealth and misdirection. Spellthieves posses the unique ability to drain or "steal" abilities and spells from their opponents and enjoy nothing more than finding creative ways to turn their own opponents attacks back against them. Spellthieves cast spells spontaneously just like a sorcerer does but have an even smaller selection of spells to use and learn, making spellthieves very practical combatants but also fairly likeable thanks to their higher than average charisma.
Spellthieves in Eberron Edit
During the Last War two organizations came upon and exploited the abilities of spellthieves, the Royal Eyes of Aundair and the Dark Lanterns of Breland. Consumate spies and assassins spellthieves were often given spellcasters as targets during the war, using their abilities and stealth to disable and then kill their quarry.
Most spellthieves have ended up much like the warforged, lost and wandering without a solid purpose to ground them now that the war has ended. Many have fallen in with criminal organizations (particularly in Sharn, Wroat and Fairhaven) or have traveled far in search of a worthy use of their powers.