You've become proficient in using a dagger in your off-hand as a defensive tool. When wielding a dagger in one hand, and a Finesse or Simple melee weapon in the other, you gain the following benefits:

• You gain +2 AC when wielding both the dagger and your other weapon. You lose the AC bonus if your dagger is stowed or you become disarmed of it.
• When attacking with the dagger as a two-weapon fighting attack, you can attempt to disarm the opponent of their weapon. The foe has to make a DC 12 Dexterity saving throw or be disarmed. This feature can be used once per short or long rest.
• If the dagger you're wielding is magical, you can use it as a spellcasting focus regardless of the dagger's properties.