Upon usage, a large amount of enmity is added to the user.
Warriors 50+ get an Enmity Bonus to provoke making it stronger than warrior subbed or a warrior 49 or less. This was stated in an interview by Square-Enix. The amount added to the bonus was not given.
In Ballista and Brenner, this ability temporarily makes you the opponent's target and prevents them from switching targets (which also prevents the opponent from using any self-cast abilities or spells).
In Besieged (And possibly other areas), provoking a charmed person puts them to sleep.