We usually follow this homebrew guide for magical item prices, and my players have recently played through the Lost Laboratory of Kwalish adventure. In it, they obtained a cursed longsword, a Blade of the Medusa. The Longsword of the Medusa restrains and petrifies the target.
When you attack a creature with this magic weapon and roll a 20 on the attack roll, the creature must make a DC 15 Constitution saving throw in addition to suffering the attack's normal effects. On a failed save, the creature is restrained and must make another Constitution saving throw at the end of each of its turns. If it successfully saves against this effect three times, the effect ends. If it fails its saves three times, it is turned to stone and subjected to the petrified condition for 1 hour.
The blade curses the user.
This weapon is cursed, and becoming attuned to it extends the curse to you. Until the curse is broken with a remove curse spell or similar magic, you are unwilling to part with the weapon. Whenever you attack a creature with this weapon and roll a 1 on the attack roll, you must succeed on a DC 15 Constitution saving throw or be restrained and forced to make additional saves against being petrified, as above.
They have now decided to sell it (we follow a homebrew world where some places have magical item markets), and I was wondering what would be an adequate value for it. It is very rare, cursed (my players don't really care about that), and looks like a very powerful weapon.
I would value the Medusa Longsword around 15000g (a bit below a +3 Longsword). Restraining the target is always useful, but there are no to-hit or damage bonuses. The effect only occurs on a natural-20, so it should be rare. I'd like to have some input from the community on my value estimation.
