Made of ebony, this curved blade sword has a sickening-looking green coloration. Tentacles are wrapped around the crossguard and extend to wrap around the hand that grips the hilt. Nevertheless, it has a +3 bonus to the damage it deals because it was made with ebony.
Proficiency with a Longsword allows the user to add their proficiency bonus to attack rolls made with this weapon.
Weapon (longsword), very rare, requires attunement
Miraak's sword was gifted to him by Hermaeus Mora. Like their pact, this weapon seems to hold onto its wielder and possibly guide them instead of being guided by its wielder, bringing new meaning to envisioning a weapon to be an extension of one's arm.
Whenever a creature attunes to the Sword of Miraak, that creature must make a DC 17 Wisdom Saving throw. On a failure, the creature becomes influenced by the spirit of Miraak still tied to the weapon. They must abide by Miraak's commands so long as they remain attuned to it. They do not wish to part with the weapon and do not possess the means to reveal the item is cursed and controlling them. They deem Miraak to be the one, and only, true Dragonborn.
On a success, they are made aware of Miraak's control. So long as they remain attuned to and wield the sword, they must abide by Miraak's decrees but they possess the capability to discard the weapon and unattune from it if they desire.
While attuned to and wielding the Sword of Miraak, the wielder gains the following effects:
The appearance of the blade instills panic in its targets. Whenever the blade hits, the target must make a DC 18 Wisdom Saving throw. On a failure, madness is instilled in the target. Roll on a DM's choice of Madness tables.
The weapon deals bonus acid damage, on hit, equal to 1d8 acid damage.
The sword also has 2 charges that refresh after a long rest. With these charges, the wielder can use an action to cast the spell Black Tentacles.