Adamantine Club

This weapon or piece of ammunition is made of adamantine, one of the hardest substances in existence. Whenever this weapon or piece of ammunition hits an object, the hit is a Critical Hit.

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.

Light: When you take the Attack action on your turn and. attack with a Light weapon, you can make one extra attack as a Bonus Action later on the same turn. That extra attack must be made with a different Light weapon, and you don't add your ability modifier to the extra attack's damage unless that modifier is negative. For example, you can attack with a Shortsword in one hand and a Dagger in the other using the Attack action and a Bonus Action, but you don't add your Strength or Dexterity modifier to the damage roll of the Bonus Action unless that modifier is negative.

Proficiency: simple, club Source: Dungeon Master's Guide (2024) p. 227