Deflector A5E
When you are wielding a finesse weapon with which you are proficient and would be hit by a melee attack, you can use your reaction to add your proficiency bonus to your Armor Class against that attack.
When you are wielding a finesse weapon with which you are proficient and would be hit by a melee attack, you can use your reaction to add your proficiency bonus to your Armor Class against that attack.
Source: Adventurer's Guide (EN Publishing) · License: Creative Commons Attribution 4.0 / OPEN GAME LICENSE Version 1.0a details