Tessen are martial, bladed weapons that consist of folding fans enforced with metal and with blades on the end that deal 1d4 slashing damage on a hit and have the Adaptable, Finesse, Light and Special properties.

Properties

Adaptable
This weapon can be used with differing techniques, allowing it to deal different types of damage. When a creature makes a weapon attack with this weapon, it can choose to deal bludgeoning damage instead.

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.

Special: Fan Shield
When you are hit by an attack made with a projectile that weighs less than 2 pounds, such as a thrown dagger, dart, arrow, or bullet, while holding this weapon, you can use your reaction to open the tessen and attempt to deflect the projectile. You gain a +2 bonus to AC against the triggering attack, potentially causing it to miss.

Superior Strike

Whirling Strike.
In a blitzing vortex of aggression, you strike at all those around you in a sinuous assault. Each creature within your reach must make a Dexterity saving throw. A creature takes damage of your weapon’s type equalling a number of d6s equal to your proficiency bonus on a failure, or half as much damage on a success. Success or failure, the creature can’t make opportunity attacks against you until the end of this turn.