Source: Tyranny of Dragons

Weapon (greatsword), legendary (requires attunement)

A sentient (neutral evil) greatsword, Hazirawn is capable of speech in Common and Netherese. Even if you aren't attuned to the sword, you gain a +1 bonus on attack rolls and damage rolls made with this magic weapon. If you aren't attuned to Hazirawn, you deal an extra 1d6 necrotic damage when you hit with it.

Increased Potency. While you are attuned to this weapon, its bonus on attack rolls and damage rolls increases to +2, and a hit deals an extra 2d6 necrotic damage (instead of 1d6).

Spells. Hazirawn has 4 charges to cast spells. As long as the sword is attuned to you and you are holding it in your hand, you can use an action to expend the required number of charges to cast one of the following spells from the sword: Detect Magic (1 charge), Detect Evil and Good (1 charge), or Detect Thoughts (2 charges). Each night at midnight, Hazirawn regains 1d4 expended charges.

Wounding. While you are attuned to the weapon, any creature that you hit with Hazirawn can't regain hit points for 1 minute. The target can make a DC 15 Constitution saving throw at the end of each of its turns, ending this effect early on itself on a success.