You've spent some time dueling for coin before local magistrates, and learned a few tricks to keep the audience guessing.

Gain proficiency with Longswords.

When you are wielding a weapon such as a longsword, quarter staff, or other versatile weapon with which you are proficient in one hand, you gain a +1 bonus to the attack roll and +1 to AC and act as if the versatile weapon were light, so long as they are wielded in your dominant hand.

Parry
While wielding a versatile weapon alongside a, light, or improvised weapon, or with no weapon in your offhand, if an incoming melee attack fails to breach your AC by 2 or less, make a single attack of opportunity in return with +2 damage. However, if an enemy melee attack breaches your AC by exactly 1, take 1d2 bonus damage as the failed parry leaves you exposed. If you manage to parry an opponent's parry, it is an automatic critical hit. You can only parry once per turn, but it does not require a Reaction. Parrying with an empty offhand means defending with your versatile weapon and making an unarmed attack against the enemy, but with advantage.

While wielding a shield in your offhand and a versatile weapon in your main hand, make an attack of opportunity with disadvantage any time an enemy makes a melee attack against you and fails to breach your AC by 5 or less. If the attack lands, roll damage at -1, or -2 if you roll the highest possible on your damage die. This can be done as many times as you are attacked per turn, and does not require a Reaction. You skillfully attack and defend at the same time.

When you are wielding a versatile weapon in two hands, add +1 bonus to the attack roll and add 1d4+2 to the damage roll.

However, so much time spent fighting in fair, melee duels has left you unused to dealing with multiple opponents or ranged attacks. You have -1 AC against non-thrown ranged attacks, or when flanked. Lose this penalty three levels after taking this feat.

This feat can alternatively be taken as a fighting style. If taken as a fighting style, the -1 to AC listed above does not apply.