I'm not The Jester, but here's my rewrite:
Powerful Smiting [General]
Your powerful strikes result in stronger smite attacks.
Prerequisites: Strength 13, Power Attack, Smite attack
Benefit: To use this feat, you must make use the Power Attack feat and take at least a -1 penalty to your attack roll. If you make use your smite ability on such an attack, you deal 50% extra smite damage to your opponent. You may make as many powerful smite attacks as you have Smite uses per day, but no more than once per round.
I altered the Prerequisite for Strength up to 13, since that is the requirement for the Power Attack feat.
I also thought it would be better to simply link the ability to the character's Smite X ability, since there could be a mismatch between smite uses per day and power smites, especially in the case of a multiclass character.