Eclipse

Eclipse is a magic sword currently wielded by Lord Hazkrakor.
It was forged during the Long Night, an era from the death of Pelor to the rise of Raos, characterised by the absence of the sun. It is unknown exactly who created the blade, other than that they were "beings of feverish intellect and foresight", who planned the forging well in advance and as such must have been able to predict Delvash's use of The Death Equation.
Eclipse is sufficiently powerful and evil that merely holding it will drive the wielder into "nihilistic insanity" unless their mind, body and soul are sufficiently united. Even a powerful dragon like Hazkrakor was not able to control it without the assistance of the Vampire King Alyssa.