You have mastered the art of the parrying dagger making you a fierce opponent in single combat. While wielding a dagger in your off-hand you gain the following benefits: 

• You may wield a weapon without the Light property in your main-hand, and your main-hand attacks may still benefit from the Dueling fighting style. 
• When you hit a creature with a weapon attack, you may use your bonus action to impose disadvantage on their next attack against you before the start of your next turn. 
• When a creature within 5 feet of you misses you with a melee attack you may use your reaction to make a melee weapon attack against that creature. If the triggering attack was made at disadvantage, you may make this attack at advantage.