Master Two-Weapon Fighting (HB)

You have learned to use your off hand equal to your main hand. While dual wielding weapons you gain an additional bonus action for a total of 2 bonus actions per turn and may attack with your offhand weapon separately with your bonus actions (Doesn't require attack action to use bonus attack).

In addition, you also increase Strength, Dexterity, or Constitution by one but not higher than 20, and gain weapon modifier damage to your offhand weapon attacks if you don't already.

Level 12+ and Dual Weapon Mastery Perk Required.