Morsblade (3.5e Equipment)
From D&D Wiki
This beautiful Bastard Sword has a smooth unmarked blade that gleams as if made of polished silver. Light that reflects off its surface is tinted a deep emerald green giving the blade an unearthly glow in any level of illumination. A black leather grip covers the dark black metal hilt, the worn leather of the hilt almost seeming to fade into the darkness of the metal. The pommel is set with a large emerald, and careful examination or insufficient external light reveals a steady gleam of illumination from the gem. This light does not suffice for any form of light-dependent vision, although it may serve to reveal the presence of the sword in the dark.
This sword was created by the Athar to help in their battle against Tiamat’s children. While they forged the blade Nicor managed to infuse the metals with a curse that would allow the chaotic taint of the Abyss to infect its wielder. Unknowing, the Athar finished the blade and put it to use; once its curse was discovered the blade was cast aside and long lost. Morsblade has all the same statistics as a normal Bastard Sword, but it’s enchantments grant it the following powers: Morsblade functions as a +4 Defender, as well as granting the wielder a boost to Strength up to 3 times per day.
Using the Strength ability of Morsblade triggers its curse. 3 times per day Morsblade can grant an Enhancement bonus of 1d4+1 to the wielder’s Strength as a standard action. This bonus ends when the wielder loses contact with Morsblade, or after 1 minute per character level of the wielder. Use of this power causes the wielder to feel oddly nauseous, and if the wielder fails a Fortitude save (DC 13 + points of Strength bestowed), the wielder gains 2 points of Taint (Corruption). If not using the Taint Rules presented in Heroes of Horror then failure results in the wielder's taking 2 points of Charisma drain. A wielder who reaches 0 Charisma immediately transforms into a Chaos Beast, with all traces of the former personality gone.