You gain following benefits

Ability Score İncrease. Increase your Dexterity Score by 1, to maximum of 20

Shield of All. When an ally attacked by an enemy around 10 feet of you. You can use your reaction to get between the enemy and your ally and hit by the enemy instead. When you do so, before the enemy's attack you take +1 to your AC until the end of the enemy's turn . You can use this feature once in every turn. 

Also if you use this feature to protect an ally that is making death saving throws, you can spend your next action to help your ally.