Preceptor: Gives +1 BS and all Armigers within 6" get better Leadership (9), allowing them to resist Pinning better and they don't fail morale as often. Remember, Armigers are not Fearless. They are only Stubborn, and so they can get swept in combat if you're not careful. Best used in a shooty Knight, e.g. a Knight Crusader. I don't think it works well for something like the Knight Castigator, who already has twin-linked, or the Knight Acheron, who auto-hits with his flamestorm cannon and has twin-linked for his heavy bolter.