Rapier Master

Through training and dedication you have become a master of the Rapier. Any DC asked of this feat is equal to 8 + your proficiency modifier + your dex modifier. 

With a Rapier: 

Disarm: As an action you may attempt to disarm your opponent. Your opponent must make either a dex or str saving throw, if they fail you may throw their weapon 5ft away from them  in a direction of your choosing. 

Corrective Strike: With your quick reflexes you can correct a missed attack. Using your bonus action you can try to correct your strike and reroll your attack. (this does not count as having advantage). 

With a Rapier and Dagger: 

If you equip a dagger on your off hand you can use it defensively. Daggers give you +2 to your AC. If a dagger were to have a +1,+2, or +3 that number would be added to your AC as well. 

Parry: When you are attacked by a melee weapon attack you may use your quick reflexes to prevent the attack from hitting. As a reaction and before the DM confirms the hit, you may double the ac bonus your dagger gives you until the start of your next turn. Changing from defense to offense takes adjustment. Your next attack has disadvantage.