The Tsurugi of Muramasa

The Tsurugi of Muramasa is the Samurai quest artifact. It is lawful for wishing purposes.

It is a tsurugi, a type of two-handed sword. It does 4-28 base damage, with a 5% chance either of instantly killing, by bisection, small monsters and monsters engulfing you, or of doing double damage to large monsters.

Its disadvantage is being two-handed; if it becomes cursed in a fight, especially in Gehennom, you cannot cast spells, reach into your bag for holy water, or in fact, do anything else with your hands.