Sentient Rapier

[KingWhipsy]

Looking to get thoughts on a Sentient Rapier my Swashbuckler Rogue started the campaign with.

It's a +1 Rapier that grants the riposte and parry maneuvers with 2 d8 superiority dice that reset on a short or long rest. In addition, the weapon grants 1 free failure on a charisma check with no repercussions per long rest. The soul inside is an old boat captain who went down with his boat and made a deal with Poseidon to be placed inside his weapon. My character found it on a seas expedition where he was a crew member of a pirating crew. Thoughts on the idea of the weapon and also on the strength of it?

[SwordMeow]

This is a very rare weapon, and it's super strong on a rogue. If your DM didn't intend for it to be very rare power level, it should be nerfed. Here's how you would optimally play it:

Stay in melee and only use riposte. Sneak attack is once per turn, not once per round, so you will get sneak attack on riposte attacks - functionally doubling your sneak damage twice per short rest provided you hit, with the d8 damage on top. Most of the time you can ignore precision. After you use both dice for riposte, do a normal Disengage as a bonus action walking in and out of melee range with your rapier. Use precision if: you are pretty sure that the enemy is close to dying (it being the last enemy) and you missed the attack by 4 or less; you need to kill an enemy before it does something (knock you to 0, knock an ally to 0, etc); and that's about all I can think of

I have no idea what a 1 free failure on a cha check with no repercussions is but it sounds neat