Unarmored Body( Races of Eberron, p. 120)
Your body is crafted without its normal layer of armor, trading off physical strength for magical potential.
1st level only, Warforged,
You lose the normal +2 armor bonus and light fortifi cation common to warforged characters, but you have no inherent chance of arcane spell failure and can wear armor or magic robes and gain their full effects.
Unlike most feats, this feat must be taken at 1st level, during character creation. If you later select any warforged feat that grants or adjusts an armor bonus or damage reduction, you lose this feat and all its effects.