Godsbane

Godsbane was the sword form adopted by Mask during the Time of Troubles in 1358 DR. Cyric named the sword "Godsbane" because, while he was a mortal, he used it to slay the god Bhaal (then Lord of Murder), and after becoming a deity, he used it to kill Leira, Lady of Deception.

History
He would eventually come to be wielded by the then-mortal Cyric. Cyric acquired the sword by murdering a halfling named Atherton Cooper, also called Sneakabout, who in turn killed the former wielder of the sword.

This was the sword Cyric used to kill Kelemvor Lyonsbane while atop Blackstaff Tower. To spite Cyric for trying to break her will while he was a mortal, Mask as Godsbane hid Kelemvor's soul from him. During a revolt in the City of Strife that marked the end of Cyric's reign as Lord of the Dead, Cyric learned of this and snapped the blade in two. This revealed the sword to be an aspect of Mask, the god of thievery and intrigue. By doing this, Cyric greatly weakened Mask and gained the portfolio of intrigue, along with shadowy characteristics. For this Mask hated Cyric, and he plotted a way to recover his lost portfolio.

Powers
Godsbane needed to consume the energy of souls to survive. "She" sucked all the blood from her victims, giving her a blood-red hue. When starved for a long time, she gradually faded to white. Before she came into the grasp of Cyric, Godsbane had driven all of her previous wielders mad, forcing them to sustain her by killing victims. Eventually, the blade would be stolen by another, and the former wielder's thoughts would always be focused on recovering it. They would never sleep until they'd recovered the blade or died trying.