When you roll a 20 with this magic weapon, the target takes an extra 7 Slashing damage.
Note: According to the SRD, it is an extra 2d6 Slashing damage, although this is incorrect.
A light weapon is small and easy to handle, making it ideal for use when fighting with two weapons.
This magic weapon deals an extra 2d6 damage to any creature it hits. This extra damage is of the same type as the weapon's normal damage.
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.
When you make the extra attack of the Light property, you can make it as part of the Attack action instead of as a Bonus Action. You can make this extra attack only once per turn.