The Chrysamere is a very powerful claymore that has been lost to time after jumping from one owner to another. In The Elder Scrolls III: Morrowind, the blade rests in a Necromancer's cave named Abanabi. The Nerevarine may travel there and kill the current owner for the weapon.
The Chysamere is one of the artifacts the Nerevarine may sell to Torasa Aram at the Museum of Artifacts in Mournhold. She offers them 30'000 for it, which is the maximum of gold she will spend for one item.