An alchemical process has bonded silver to this magic weapon. When you score a Critical Hit with it against a creature that is shape-shifted, the weapon deals one additional die of 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.
If a weapon has the Thrown property, you can throw the weapon to make a ranged attack, and you can draw that weapon as part of the attack. If the weapon is a Melee weapon, use the same ability modifier for the attack and damage rolls that you use for a melee attack with that weapon.
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.