Having further mastered the usage of dual wielding, you've reached a height that few swordsman can obtain with your weapons

While dual wielding, you may use your bonus action to attack a number of times equal to that of the amount of attacks you can do with one attack action
(For example, a level 20 fighter can throw out 4 attacks as a Bonus action.) However, attacks made this way come with a Drawback
The First Attack has No Penalty
The Second Attack takes a -5 to the Roll
The Third takes a -10 to the Roll
and
The Fourth takes a -15 to the Roll.

Aswell as gaining access to a unique reaction that allows you to take half damage on a fail and no damage on a pass against Dex saving throw based AOEs.(Passing this way does not spare you from any lingering effects)

You also gain an additional +1 to your Armor Class while Dual wielding