Hidden in an unexplored dungeons was Zuno, a magical sentient sword.

You gain a +1 bonus to attack and damage rolls made with this weapon. This bonus increases to +2 at 17th level and to +3 at 20th level.

While holding her, she acts as a Focus for your spells.

If either of your hands are empty, you can use an action to summon her into your hand. If you are holding her, you can shunt her off into an extra dimensional space whenever you want, no action required.

Spin Attack

Zuno can float and has a movement speed of 30 feet. She shares your Initiative and takes her turn immediately after yours.

She can decide to use any of the normal actions. She can decide to attack, upon which she spins through the air, which has an attack bonus of +10 and deals 1d8+4 slashing damage. This damage counts as magical for the purposes of overcoming resistances and immunities.

Se can also decide to protect you, which increases your AC by 2 until your next turn.

Supernatural Knowledge

You can ask Zuno ask any question 3 times per day. The DM chooses the extend of the answer. All charges are replenished on the next dawn.

Protector

While you hold her, any mental status effect that affects you has a chance of affecting Zuno as well.

Zuno can choose whether to cast Haste, Hex or Invisibility for you three times per day. She maintains concentration on these spells so you don't have to.

Transformation

Zuno can transform into a female humanoid. In this state she has a walking speed of 30 feet. She can still use any of her other features but she now has an AC of 17 and 85 HP. If her HP is reduced to 0, she transforms back into her sword form and she cannot use this feature again until she has regained all of her HP.

Healing spells, potions etc work like normal on her in her transformed state.

In her sword state she can only regain HP by either slaying creatures or by taking a long rest. If she slays a creature she regains HP equal to the amount of damage you deal with her.

While she is transformed you get a regular +1 Rapier, with which you can attack. Zuno's weapon is similar in appearance to her other form and has the same modifiers.

Sentience

Zuno is a sentient chaotic good weapon with an Intelligence of 17, a Wisdom of 14 and a Charisma of 12. She has hearing and darkvision out to a range of 60 feet.

She can speak, read and understand Common and Primordial and can communicate to her wielder telepathetically. While you are attuned to her, she can also understand any language that you know.

Personality

Zuno speaks with a somewhat feisty tone, as a Tsundere would. After being discovered by Zorthor, making a pact with him and having been on countless adventures with him, she eventually fell in love with him. From that point on she wanted to protect him and do anything she could to help him grow.

Despite their differences, she swore to herself that she would never betray him.

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

Notes: Bonus: Magic, Hexblade Warlock, Damage, Combat, Finesse, Vex