Elan's rapier (Chaos Sabre)

You have a +1 bonus to attack and damage rolls made with this magic weapon, the bonus increases to +2 against creatures with a lawful alignment

While attuned to this weapon, you learn the Vicious Mockery cantrip, (Save DC 8 + your charisma modifier + your Proficiency bonus) if you already have the Vicious Mockery cantrip, the damage instead increases by 1. when you use this cantrip, instead of saying magically charged insults, you instead say magically charged puns.

You have expertise in the Performance skill, and your intelligence decreases by 2 (to a minimum of 1) when attuned to this weapon

Additionally, when you make an attack with this weapon, you can add your charisma modifier to either the attack and damage rolls if you say a pun before making the attack, this effect can be used a number of times equal to your charisma modifier (minimum of 1) and cannot use it again until the next dawn, and cannot be used if you are in an area of magical silence, currently under an effect that prevents you from speaking clearly, or are suffocating. If you have the deafened condition and use this property, roll a d4, on a 1 you misspeak and the effect fails

Lastly, if a creature fails a saving throw against a vicious mockery spell cast by you, you can make one attack with this weapon against that creature as a bonus action.

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, Damage, Combat, Finesse, Vex