Weapon Expert

Additional Fighter Feature - 3rd level

Your expertise in the battlefield allows you to use weapons like no one else. Choose a weapon trait from the list below. You can use a weapon trait once (no action required), regaining the ability to do so again when you finish a short or long rest, or by expending a use of your Second Wind feature.

Some weapon traits have prerequisites, such as the damage type of the weapon or a weapon property in specific. You can choose an additional trait whenever you gain an Ability Score Improvement, and you can change a chosen trait on a long rest.

• Puncture. Prerequisite - Piercing Damage. Whenever you hit a creature with an attack from a weapon that deals piercing damage, if there’s a creature within 5 feet of the hit creature, you may angle your strike and choose to pierce deeper to have that second creature take half of the attack’s damage.
• Concuss. Prerequisite - Bludgeoning Damage. Whenever you hit a creature with an attack from a weapon that deals bludgeoning damage, you may strike at their head and reduce the creature’s speed by half until the beginning of your next turn. While their speed is reduced, they have disadvantage on Wisdom checks.
• Wound. Prerequisite - Slashing Damage. Whenever you hit a creature with an attack from a weapon that deals slashing damage, you may slash deep and have that creature take slashing damage equal to half the attack’s damage at the beginning of its next turn.
• Brutal. Prerequisite - Heavy Property. Whenever you hit with an attack with a weapon with the Heavy property, you may choose to put your whole body into the blow, causing you to not roll for damage, taking the maximum amount on the die instead.
• Extend. Prerequisite - Reach Property. Whenever you make an attack with a weapon with the Reach property, you may fully wield its length. Until the beginning of your next turn, the additional range granted by the Reach property is increased by 5 feet, to 10 feet; and the damage die of the weapon increases by one category.
• Parry. Prerequisite - Lacks Two Handed or Ranged Property. Whenever you make an attack with a weapon that lacks the Two Handed or Ranged properties, you may brace for defense. Until the end of your next turn, your AC increases by 1, and you gain an additional +1 against ranged attacks only.
• Marked. Prerequisite - Ranged Property. Whenever you make an attack with a weapon with the Ranged property, you may focus your full attention on them. All attacks you make with the weapon against that creature until the end of your turn cannot have disadvantage and are made with advantage.
• Swift. Prerequisite - Light Property. Whenever you make an attack with a weapon with the Light property, you may fully harness its low weight. Until the beginning of your next turn, your speed increases by 10 feet, and you can make one additional attack next time you take the Attack action, as long as you attack with a Light weapon.

DISCLAIMER: DnDBeyond programming doesn't let me do a lot regarding this, you'd have to add the traits manually.