Your armor is a second skin, not only do you find it easier to cast spells, wearing armor as a whole has become less burdensome.
Prerequisites: Proficiency with Armor of the appropriate type, Class ability allows casting spells without arcane spell failure chance for light or heavier armor.
Benefit: If your class ability does not nullify the arcane spell failure for armor you are wearing, the chance is reduced by 10% (min 0%). If you may cast spells without suffering arcane spell failure for the armor worn, your armor check penalty is decreased by one (min 0) and your maximum Dexterity bonus is increased by one.
Reworked from Arcane Armor Training.