Sai are martial, sharp melee weapons consisting of three short, metal prongs that deal 1d4 piercing damage on a hit and have the Finesse, Light and Parry properties.

Properties

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.

Light
When you take the Attack action and attack with a Light melee weapon that you’re holding in one hand, you can use a bonus action to attack with a different Light melee weapon that you’re holding in the other hand. You don’t add your ability modifier to the damage of the bonus attack, unless that modifier is negative. If either weapon also has the Thrown property, you can throw the weapon instead of making a melee attack with it.

Parry
This weapon has been designed to help you parry blows. While wielding this weapon, you can use your reaction when you are hit by a melee attack to gain a +2 bonus to AC against the triggering attack, potentially causing it to miss.

Superior Strike

Skewer.
In a thrusting strike, you attempt to skewer an enemy with your weapon. Make an attack roll against a creature within your reach. On a hit, the target suffers the attack’s normal effects and is also grappled by you. This grapple ends early if you use the weapon to make another attack or you let go of the weapon. When the grapple ends, the creature takes piercing damage equalling a number of d8s equal to your proficiency bonus.