Whip

Slow (Mastery): If you hit a creature with this weapon and deal damage to it, you can reduce its Speed by 10 feet until the start of your next turn. If the creature is hit more than once by weapons that have this property, the Speed reduction doesn't exceed 10 feet.

Finesse: When making an attack with a Finesse weapon, use your choice of your Strength or Dexterity modifier for the attack and damage rolls. You must use the same modifier for both rolls.

Reach: A Reach weapon adds 5 feet to your reach when you attack with it, as well as when determining your reach for Opportunity Attacks with it.

Proficiency: martial, whip Source: Player's Handbook (2024) p. 215