It's said that this masterwork of a longsword was made priests of Gond in tandem with clerics of Milil, and that the song and warcries of the Lord of All Songs are imbued into the metal.
You have a +2 bonus to attack and damage rolls made with this magic weapon. On a hit, it deals an extra 2d8 psychic damage. (The +2 bonus also applies to the psychic damage from the regular meelee attack and to the one from shrieking.)
Divine Music: Once every short or long rest, you can make the sword sing or shriek. A creature must be able able to hear the wielder for the effektus to take place. The effects take place within a 60 feet radius. The music lasts 10 turns, unless cut short (by the wielder being silenced or killed, stopping the music or activating the other type of music, or the sword leaving its wielder's hands). The effects don't take place if the wielder is silenced, or if the music is drowned out by another sound. If the creature leaves the radius, or can no longer hear the music, the effeczs end for them. If they reenter before the music ends, the effects are reapplied until the end of the music (not for another 10 turns). The wielder can end the music early with a bonus action. The sword can't sing and shriek at the same time. (This is an ability.)
Sing: The sword sings a divine melody. All nearby allied or friendly creatures receive the effects of Bless for the duration, and all nearby hostile creatures are charmed. Every time one of these creatures has damage dealt to them by the sword, they can make a Charisma saving throw to end the effect early.
Shriek: The sword releases an earpiercing warcry. All nearby hostile creatures must succeed a Charisma saving throw or be frightened for the duration. Regardless if they failed or succeeded, they take 1d8 psychic damage every turn for the duration.
If the sword gets into the hands of a creature other than the attuned, they gain the Ire of the Choir condition until the sword leaves their posession, or if they attune to the sword themself.
Ire of the Choir: The creature has disadvantage on all checks, Charisma saving throws, and receives an additional -3 penalty to any Performance check requiring the use of the creature's voice. (This is a condition.)
Proficiency with a Longsword allows you to add your proficiency bonus to the attack roll for any attack you make with it.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Sap. If you hit a creature with this weapon, that creature has Disadvantage on its next attack roll before the start of your next turn.
Notes: Bonus: Melee Attacks, Damage: Psychic, Charmed, Frightened, Versatile, Sap