Cymrith (Patreon)

Weapon (rapier), legendary (requires attunement)

Forged by elven smiths to thwart the rising tide of evil among them, Cymrith has played a pivotal role in numerous fey confrontations. Thanks to its powerful magic, relentless bloodshed could be turned to peaceful negotiation. If you are fey or have the Fey Ancestry trait, you are proficient with Cymrith and can use your Charisma modifier for attack and damage rolls with it, instead of Strength or Dexterity.

You gain a +3 bonus to attack and damage rolls made with this magic weapon, which ignores resistance to piercing damage. Any fey hit with this weapon takes an extra 2d6 psychic damage from the attack. You also gain a +3 bonus to any Charisma check made to interact with fey.

This weapon has 3 charges and regains 1d3 expended charges daily at dawn. When you reduce a creature to 0 hit points and choose to knock it out, you can expend 1 or more of the weapon's charges to force that creature to make a Wisdom saving throw (save DC 17). On a successful save, the creature is immune to this effect for the next 24 hours. On a failed save, that creature is affected by the modify memory spell (no concentration required). You can speak to the unconscious creature for the duration of the spell to describe how its memories are affected. When the spell ends after 1 minute, the creature regains consciousness with 1 hit point. For 1 charge, you cast the 5th-level version of the spell. You can increase the spell slot level by one for each additional charge you expend.

Sentience. Cymrith is a sentient chaotic good rapier with an Intelligence of 10, a Wisdom of 14, and a Charisma of 18. It can hear and has darkvision out to a range of 120 feet. It can speak, read, and understand Common, Elvish, and Sylvan, and can communicate with its wielder telepathically. Its voice sounds silvery and melodic.

Personality. Cymrith yearns for the destruction of evil fey creatures and urges you to seek out these creatures and either kill them or turn them toward the path of good.

As it turns out, not even the fey trust the fey.