Alright, so I want to make Duel of Wills a potent option for a character; therefore, I went out and searched out things that could buff it up.
So far, I've found these things:
Unnerving Calm: Use Concentration instead of Intimidate for Duel of Wills; it also gives a +4 to your check and makes it so if they ignore you, the Morale Bonus to attack rolls is +2 instead of +1.
Perfect Clarity of Mind and Body: If you win a Duel of Wills, you get a +4 morale bonus on Trip, Disarm, and Feint an opponent.
Reforged 3rd Level Benefit: Any Morale bonus you receive is increased by +1.
Battlebred feat: Any effect that grants you a Morale bonus is extended by 2 rounds.
End result: You challenge a dude to a duel of wills; there are 3 options:
They submit, and take a -2 to Initiative and a -1 to attack rolls for one round.
They ignore you, and you get a +3 on attack rolls against them for 3 rounds.
They return the challenge; if you win, you get a +5 bonus on Trip attempts, Feints, and Disarm attempts for 3 rounds, and have a +2 bonus on attack and damage rolls against them for the encounter.
Now, if only there was some way to apply a Duel of Wills to more than one guy, or something...