Kikoku

Kikoku is a single-edged sword built on the oversized odachi pattern, running roughly 140 centimeters in length. Its size pushes Law to rest it on his shoulder rather than at the hip or back, and at times he hands it off to a crewmate such as Bepo to carry. The hilt is bound in periwinkle cord over darker samegawa, wrapped at the center with a white bandage, capped in gold fittings, and crowned by a round guard fringed in short white fur. A black-lacquered sheath marked with rows of white plus signs, accented by a red cord near the mouth, completes its look. The wiki notes the blade ranks as a famous one yet sits ungraded, and is additionally labeled a cursed sword.

Because Law so often routes his Devil Fruit power through Kikoku, the blade's own cutting quality is hard to gauge; it acts less like a normal sword and more like a surgeon's scalpel or injection needle, severing or piercing targets without physical force. At full strength he has split an entire mountain range and even a falling meteor. On its own the steel proved tough enough to halt Doflamingo's strings, a feat most weapons cannot manage without Armament Haki. Through it Law performs his core moves, from Amputate, which separates a body without harming it, to the electrified Radio Knife that blocks reattachment, the stabbing Injection Shot, and the buzzsaw-like Sterben. Awakening adds K-ROOM coated strikes such as Anesthesia, which phases through anything, and the devastating Puncture Wille and Shock Wille, both of which bypass external defenses to wound from within, as shown against Big Mom.

Trafalgar Law is the blade's wielder throughout the series, and the name Kikoku, an archaic term for the wail of a restless ghost, is read as a reflection of his vow to avenge Donquixote Rosinante. Non-canon material expands its lore: the curse, dubbed the Oni Wail, drains the life of anyone who swings it, and across two centuries only an ancient swordsman from Wano and Law himself are said to have tamed it, each bending the blade through sheer force of will. Oda also drew a personified version of Kikoku in an SBS column, picturing it as a weary, mustachioed man.