Source: Player's Handbook

Prerequisite: Level 4+

You gain the following benefits.

Ability Score Increase. Increase your Strength or Dexterity by 1, to a maximum of 20.

Puncture. Once per turn, when you hit a creature with an attack that deals Piercing damage, you can reroll one of the attack’s damage dice, and you must use the new roll.

Enhanced Critical. When you score a Critical Hit that deals Piercing damage to a creature, you can roll one additional damage die when determining the extra Piercing damage the target takes.

Swift Stab. Whenever you make a melee attack that deals piercing damage against a creature and miss, the target takes piercing damage equal to half of your proficiency modifier (rounded down).