Ok,
With the new classes coming out (especially the Samurai), it got me to thinking about old movies. Especially the Zatochi and Seven Samurai movies. One of the bits of realism they had was that most duels tended to end on the first attack. Someone usually ended up dead in a duel very quickly.
So, I was trying to come up with a mechanic to simulate this, and this is what I have so far.
Combat Maneuver : Duel
Unlike most combat maneuvers, this maneuver requires two willing enemies. To initiate, an combatant takes a stance indicating an invitation to duel, often accompanied by words to such effect. If the opponent accepts the invitation, the two begin to circle each other. They start a distance apart equal to the smallest reach between the two of them. As they circle, they are looking for an opening. This process takes 1d4+1 turns, and the two combatants are at -4 AC to all outside attacks.
Once the indicated number of turns have passed, the two combatants make an combat maneuver attack. Any feats that may be used with a full attack action may be used with this maneuver. Effects that increase or decrease attack bonus (such Enhancement Bonus to weapons used, or power attack) may be used, and the attack bonus or penalty affects the CMB of the attacker.
If the maneuver is successful, the attacker is treated as having scored a critical hit with their weapon. Both characters can make a critical hit, if both are successful. If an attacker threatens an actual critical, and confirms it, the critical multiplier is doubled.
After the duel is complete, the two enemies end up in the opposite squares they started from (exchanging positions), but facing away from each other. If both are still alive, and wish to continue, they may either initiate normal combat, or continue with another duel check.
Draw Weapon
A duelist can start with their weapon sheathed. This only applies to weapons that are normally sheathed, such as swords, daggers, or rapiers. The duelist may, as part of the maneuver resolution, draw their weapon from the sheath. The extra motion of the weapon grants the attacker a damage bonus equal to their STR bonus, but applies a CMB penalty of -2. If the attacker has any feat or ability that allows them to ready the weapon as a free or swift action, the penalty is negated. If the attacker is using multiple weapons, the penalty is per weapon. Thus drawing two weapons as part of the attack applies a -4 penalty to CMB.
Dual Weapons
A duelist can use two weapons with their maneuver. The duelist applies the penalties/bonuses for his weapons to his CMB as normal for two weapon fighting. Each weapon does crit damage on a successful attack, and each does double damage if confirming an actual critical.
Notes : Yes, I intentionally picked CMB/CMD as the mechanic, this puts everyone on an equal footing (actually, heavy armor tends to degrade CMD). This is absolutely a cinematic type maneuver, it's intended as something that has to be entered into willingly, and it's not designed for doing in the middle of a big fight.