Nunchuck of Warning

Nunchucks are martial melee weapons composed of two hard batons connected to one another by a short chain.

This magic weapon warns you of danger. While the weapon is on your person, you have advantage on initiative rolls. In addition, you and any of your companions within 30 feet of you can't be surprised, except when incapacitated by something other than nonmagical sleep. The weapon magically awakens you and your companions within range if any of you are sleeping naturally when combat begins.

Special: Flourish. When you are wielding the nunchucks in two hands and take the Attack action on your turn, you can attempt to flourish with the weapon immediately before you make your first attack. To flourish, make a DC 13 Dexterity check, adding your proficiency bonus if you are proficient with nunchucks. On a success, you gain a +2 bonus to the first attack roll you make this turn. On a failure, you deal bludgeoning damage to yourself equal to your proficiency bonus and gain no bonus from your flourishes this turn.

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

Versatile: This weapon can be used with one or two hands. A damage value in parentheses appears with the property—the damage when the weapon is used with two hands to make a melee attack.

Proficiency: martial, nunchucks Source: Dungeon Master's Guide (2014) p. 213, Heliana's Guide to Monster Hunting - Part One