The rune of unyielding steel strengthens anything, even a living creature's skin, to the point that arrows and blades bounce off it.

Encounter   ✦     Divine
Standard Action      Melee 1

Target: One ally

Effect: The target gains a +2 power bonus to all defenses until the end of your next turn or until he or she is no longer adjacent to you.

Published in Player's Handbook 3, page(s) 104.