PRO:
- has an advantage 1-on-1 against nearly all melee combatants
- rewards teamwork with another melee character
- high mobility at short distances
- if it comes out strong and does not synergize with other combat trees you can spend your skill points on other stuff

CON:
- most skills work only melee one-handed and when you can see the target (no Riposte against attacks from the rear)
- does not have much and not often utility outside melee engagement (but it is no one-trick-pony either)
- comes into a vulnerable state when faced for too long or at disadvantageous odds
- cannot stack too much damage for ... reasons (hopefully)
[EDIT]: Main attribute is lots of Perception?
Abilities:
Drunk Swallow(active): 0 AP, 3 turns cooldown
Leap 1m between the enemy lines without provoking opportunity attacks.
Piercing Thrusts(passive):
Critical strikes cripple the target.
Pirate's Buddy(active, melee): 1 AP, 3 turns cooldown
You move within in the rear of target foe until your next turn. Ends your turn.
Parry(active): 2 AP, 4 turns cooldown
You evade the next 3 attacks.
Riposte(active): 2 AP, 5 turns cooldown
Whenever a melee enemy misses an attack against you within 2 turns, you respond with an opportunity attack.
???(active): 1 AP, 5 turns cooldown:
High awareness allows for opportunity attacks when nearby enemies move, turn around or attack others than the Duelist. 2 Turns.
Point in Line(active): 2 AP, 3 turns cooldown
Heavily punishes the first foe to approach the Duelist within 2 turns.
Remise(active): 1 AP, 8 turns cooldown
Whenever you miss a regular melee attack within 4 turns you gain an opportunity attack.
Poke(active, melee): 1 AP, 6 turns cooldown
Interrupts the next enemy spell with an opportunity attack.
Lunge(active): 1 AP, 6 turns cooldown
You enter a stance that allows you to gain increased range. Your next regular or opportunity attack
will result in a leap forward. (Opportunity attacks are provoked from farther distances, too)
(Mind that my knowledge does not surpass the unrivaling amounts of wikipedia)