Feat: Duelist's Challenge

Select one enemy you can see and proclaim a challenge against it. That enemy is your dueling opponent until it's defeated, it flees from the encounter, or the encounter ends. Any time you hit that enemy using a single one-handed melee weapon while your other hand or hands are free, you gain a circumstance bonus to the Strike's damage equal to the number of damage dice your weapon deals.

If you attack a creature other than your dueling opponent, you take a circumstance penalty to damage equal to the number of damage dice your weapon deals.