"When your Power Word: Shield is completely absorbed or dispelled you are instantly energized with 2.5% of your total mana, and you have a 100% chance to energize your shielded target with 2% total mana, 8 rage, 16 energy or 32 runic power. This effect can only occur once every 12 sec."

Currently only the former aspect of this description works at all. I have never seen the latter aspect proc any mana, rage, energy, or runic power.