Per hotfix notes on April 26:

Priest
Holy
Habiliments of the Empyrean 2-piece set bonus now increases the cooldown reduction of your next Holy-Word-affecting spell by 10 seconds when engaged in combat with enemy players (was 15 seconds).

Need to add PvP checks to Holy and use the appropriate reduction value.

The adjustment as it currently stands will change the cooldown amount calculation from 15 to 10 sec if PvP talents are currently usable. This doesn't 100% map to how this hotfix works, though, as it only causes the reduction to occur if you're currently in PvP combat with another player. A few open questions:

• Is it always set to true if you're in an arena/bg or if it's only specifically if you're in active combat with another player?
• How do we detect we're in combat with another player?
• Do mind control abilities in PvE content cause this to trigger?

This change shouldn't have any effect on MOST PvE content so it should be relatively safe.

Check and see if IsInActiveWorldPVP() does the trick or not.

IsInActiveWorldPVP() does not work.

Going to roll with the way this is implemented. Will keep an eye out for feedback.