Prerequisites - Str 17

Shield

This item looks like a gauntlet, but when you take a defensive posture by holding your arm up, a retractable shield forms.

In gauntlet form, it gives no AC bonus and does not count as armor worn.

In gauntlet form, you may use two weapon fighting. As soon as the Guardian Shield is activated, you must wait for the Guardian Shield to be retracted to use two weapon fighting again. You do not lose grasp of the weapon held in your hand. 

You may use a bonus action to activate the Guardian Shield giving you a +2 to your AC while the shield is activated, or a bonus action to retract the shield, bringing you AC down by 2.

Counter. You may use the Guardian Shield as a reaction to being hit by a melee weapon attack. On this reaction, make contested Dexterity checks. If you win, you take no damage, and may also take an attack of opportunity against the attacking creature. If you lose, you take half damage. The Guardian Shield remains activated until you retract it. You must use a bonus action on your turn to retract the Guardian Shield.

Magical Deflection. You may use the Guardian Shield as a reaction. When you do this, you may impose disadvantage on a ranged spell attack that would otherwise hit, forcing the creature to reroll and use the lowest roll. When you use this reaction the ranged spell damage is halved against you. You may use this reaction as a response to the magic missile spell. The Guardian Shield remains activated until you retract it. You must use a bonus action to retract the Guardian Shield.

Notes: Bonus: Armor Class