Armor Material Expertise (Armor Mastery, Combat)Source Armor Master's Handbook pg. 16
You tap into the potential of your armor’s special material.
Prerequisites: Base attack bonus +6 or fighter level 4th, armor training class feature.
Benefit: When wearing armor made of one of the materials listed below, you can use the listed ability twice per day (unless otherwise stated).
Adamantine: As an immediate action after being struck by an attack, you convert half the lethal damage of the attack into nonlethal damage.
AngelskinUE: As a swift action, you shine with bright light as daylight for 1 round.
Darkleaf ClothUE: As a swift action, you gain the woodland stride druid class feature for 1 minute.
Dragonhide: As an immediate action when you take energy damage of the same type to which the dragonhide armor is immune, you reduce the damage taken by 10 hit points.
Elysian BronzeUE: As an immediate action after being struck by an attack from a magical beast or monstrous humanoid, you convert half the lethal damage of the attack into nonlethal damage.
Fire-Forged SteelUE or Frost-Forged SteelUE: As a swift action, any unarmed strikes, shield bashes, or attacks with a spiked gauntlet or armor spikes you make are treated as having the flaming special ability (for fire-forged steel) or the frost special ability (for frost-forged steel) for 1 minute.
Horacalcum (Pathfinder Adventure Path #61: Shards of Sin): Once per day as a swift action, you can grant yourself the benefits of haste for 1 round.
Living SteelUE: As an immediate action after being struck by an attack with a metal weapon, you can use the living steel’s ability to damage metal weapons, as if the attacker had rolled a natural 1 on the attack.
Mithral: As an immediate action, you gain spell resistance against transmutation spells equal to 5 + the armor’s enhancement bonus + your character level for 1 round.
Noqual (Pathfinder Adventure Path #61: Shards of Sin): The armor’s resistance bonus on saves increases to +4 for 1 round.Source Armor Master's Handbook pg. 20 (Amazon)
You can spend 5 stamina points to use an ability for a material, even though your armor isn’t made of it. This still counts against your daily limit of armor material abilities. (See page 16.)