One of the five elemental Patternblades, Justice is one of the blades that was guarded by Daffyl, the guardian serpent for many centuries, within his tower hidden in Shadow, and the first of the Patternblades to have been retrieved by Amber.
Mickelfang is a plain grey double-edged broadsword with a faintly glowing blue-white tracery upon it, depicting a portion of the Pattern. Its hilt and crossguard is made of a grey metal, plain and solidly built. The grip is wire-bound grey leather, simple and functional. The blade itself has power over Truth... a person who is attuned to it and weilding it can detect truth and lies spoken by other people. However, truth is a double-edged sword -- while the wielder holds it, he or she cannot speak any lies either, even casual ones, lest they risk being shocked by the sword. Spells and other magic that affect the mind or cause illusions can be countered or dispelled by Justice. Justice also has the power to enforce Oaths -- any serious oath pledged by a person or group on the sword becomes unbreakable; those who try to break it become Blood Cursed for their transgression.
Justice also has the usual suite of Patternblade abilities -- high damage value, spellbreaking, setting Chaos blood aflame, etc.
Micklefang awaited the "The King of All Colors and None" to draw it forth from Daffy's Tower. The first King of Amber, Gendo, was this man, and after solving a riddle game posed to him by Daffyl, was allowed to enter and draw the sword, worthy for a future ruler. He then returned to Amber to rule with the sword at his side.
After King Gendo passed away, the sword was buried with him, though later stolen. It was recovered by his descendant, Ota 'Shaft' Tenjou, lost by him, recovered by him again, used to seal away Annadil, then held by him for the next 40 years. Upon Shaft's death, it was passed on to his daughter Jacqueline, who lost it, then regained it thanks to Moriya, and is the current wielder of the blade.