Touched by the Light is a talent in the protection tree, you will need to spend 43 points in protection tree to max it.
Prior to Patch 3.0.2, Paladins wishing to tank were required to stack +Spell Damage and use caster weapons in order to build threat through their spells, which also made it somewhat difficult for tanks to build their Defense and health pools. This talent alleviated that by allowing Paladin tanks to have a decent amount of spell power for their abilities without having to enchant or gem for it.
As of Patch 3.2.2 the talent is based on Strength not Stamina.
