This jet black obsidian dagger pulses faintly with an acrid aura of Abyssal energy. You have a +1 bonus to attack and damage rolls made with this magic weapon. As a bonus action you can slap the blade on your wrist and it will transform into a bracelet. In this form it appears to be a mundane obsidian bracelet. Only an attuned creature can trigger this transformation. You can then use a bonus action to transform it back into a dagger. When thrown, the dagger returns to your hand or wrist at the start of your next turn. 
When attacking a surprised creature, you can add 1d10 to the weapon's damage roll. 

Proficiency with a Dagger allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Damage, Combat, Jewelry, Wristwear, Finesse, Light, Thrown, Nick