Dark Sun: The Scorched World of Athas
The Blade Perilous
The black blade glows a ghastly red, leaving a fading phosphorescent trail of crimson in the air. Although it is the size of a greatsword, its enchantments make it as light and easy to wield as a short sword.
This sword was taken by Way-lynn after they defeated the Lord High Exultant.
The sword compelled Way-lynn to kill Torakas after he was rescued from the dungeons. Delen subsequently determined that the blade has some amount of sentience about it.
It was carried by Thea who appeared to be more resistant to its desires to slay those with formal martial training. However, after she gave into the swords wishes, she relinquished the blade to Torakas.
Torakas was carrying the blade when he fell to his death at the base of the Spire of Black Ice in Moil.