The weapon has elvish writting on the hilt, which describes the power of the blade and a warning to whomever may use it. the main users are elvish warriers and members of a royal family as it is normally handed down a family line. The blade is made of platinum which shines mother of pearl and when commanded to it can submerge itself in boiling water which can get up to 110 degrees. The attacker can not withstand the blade near them or on there skin, as the blade enters the body the boiling water will burn them from the inside out within a matter of seconds.
A PC Conjurer or summoner, basically any mage whose sole purpose in life is summoning creatures to aid in battles and various situations, is cursed with a hex, and needs to find a way to undo the curse...before he goes mad, or his fellow PCs throw him out of the party, or worse.
Everything he/she summons, never goes away. So you'll have to figure out what the heck to do with that dire bear or fire elemental once it's done fighting the orcs for you. Eventually a caravan of bizarre creatures either annoyingly ends up following the summoner around, or they go off to cause mayhem elsewhere. Bad news for the poor spell-caster regardless.