Martial Weapon Master.

Prerequisites: Must have martial weapon proficiency, and a strength or dexterity score of 16 or higher 

Your skill with your favored weapon has grown to rival true masters of battle. Pick one martial weapon as your favored weapon, and gain the following benefits:

• You learn three maneuvers from the Battle-master maneuver list. You can only use these maneuvers while you wield your favored weapon. You have a number of D8 superiority die equal to your proficiency bonus minus one to fuel your maneuvers which you gain back on a short or long rest.
• You learn one fighting style, you may only benefit from this fighting style if you are wielding your favored weapon. You cannot take the same fighting style twice if you already have one.
• On a turn in which you made an attack with your favored weapon, you may push yourself beyond your normal capabilities and make one additional attack with your favored weapon. You can only use this feature once per short or long rest.