You've learned where to cut to have the greatest results, granting you the following benefits:
Increase your Strength or Dexterity by 1, to a maximum of 20. Once per turn when you hit a creature with an attack that deals slashing damage, you can reduce the speed of the target by 10 feet until the start of your next turn. When you score a critical hit that deals slashing damage to a creature, you grievously wound it. Until the start of your next turn, the target has disadvantage on all attack rolls.