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.
The secret for immortality has been discovered by an eccentric wizard/mad scientist. Its found you need to reapply once a month. As people stop dying, and the birth rate increases exponentially, people are forced into homelessness, because of the need for food reamins the same, and food is not being produced fast enough to feed the undying population. The PCs have to find the creator and kill him, and destroy production, to save the world from undying, unending torture from hungryness.