How would you create this homebrew feat?

[Xrposiedon]

So I got an idea from Volo's when I saw a picture of the Fire Giant Dreadnought.

A feat where you can use two shields....

How would you all go about creating such a feat so it didn't break the game?

[Arkhios]

So I got an idea from Volo's when I saw a picture of the Fire Giant Dreadnought.

A feat where you can use two shields....

How would you all go about creating such a feat so it didn't break the game?

I would probably make something like this:
You gain proficiency with a shield as a one-handed martial weapon which deals 1d8 bludgeoning damage.
In addition, you gain the following options:

As a reaction you can bestow disadvantage against an attack roll against you.
As a reaction you can gain advantage against a Dexterity saving throw.

As an additional clause, however, I would add a line saying that you can only ever gain a bonus to your AC from one shield.