Quicksword

The Quicksword "Enilno" is found in Ultima II in the city of New San Antonio, in 1990 A.D.. The strongest weapon available in the game, it is also required to complete Ultima II.

During the quest to undo the damage done to the timeline by Minax, the Stranger discovered that the sorceress could only be hurt with a special weapon -- the Quicksword, "Enilno." Unfortunately, the owner of the sword, Sentri, was bring held in the New San Antonio prison. The Stranger had to break into the prison and free Sentri, who sold him the sword for 500 gold. With the Quicksword in hand, the Stranger was later able to defeat Minax.

Trivia

 * As an easter egg, the Quicksword can be found in the Underworld of Ultima V: Lazarus. It is the part of the Underworld under the dungeon Hythloth.
 * "Enilno" is "Online" backwards, a possible nod towards Ultima II publisher Sierra Online.