Chaos Sword

The Chaos Sword is a weapon encountered in Ultima V. However, just because one can acquire something does not always mean one should...

Rumors had reached the Avatar that Lord Blackthorn possessed a special sword, stored in a chest covered in Human skin -- the Chaos Sword. The forces in this sword were said to be so horrible that it would force the wielder to slaughter his or her own friends in a fit of madness. Virtuous as the Avatar was, the hero resisted the temptation to recover it from Castle Blackthorn when it was possible.

It is unknown what happened to it, but hopefully Lord British destroyed this horrible weapon after returning to power.

Trivia

 * According to the Prima Guide to the Ultima Collection, the Sword of Chaos has a 99(!) damage rating, which is equal that of to a Glass Sword.
 * The Chaos Sword disappears after the first time it is used in combat.