Duelist

Prerequisite: at least 13 dexterity.

When you are 1v1ing someone you have advantage on dexterity saving throws

You gain the riposte maneuver from the battle master. Add the d8

You may either be a defensive duelist or an offensive duelist

defense: you gain +1 AC when 1v1ing someone.

offense: you may add a d8 to your attack damage a number of times per short rest equal to your dexterity modifier.