Solitude, Castle Dour, carried by General Tullius. If you side with the Stormcloaks, you can kill him and loot it from him during the Civil War questline. If you side with the Imperials, it can only be pickpocketed from him.
Requires Royal Armory.
"Tullius received the sword from the emperor himself and the emperor spared no expenses. During the Great War, Judgement saw much use, and the sight of this weapon held high became a beacon of hope for the Imperials on any battlefield."