The Angel's Crescent is a special Scythe, rumored to have fallen from the heavens on a crescent moon, hence it's crescent-shaped blade. It was first discovered sometime between First Cities and Before Orlais.
Sometime during Before Orlais, nearly five hundred years ago, Angel's Crescent fell from the heavens, and was taken up by a merchant who found in a hillside 5 miles south of Orlong's Hearth. This merchant traveled north, through the lands that would later be united and named Tosconna and Fiefmont, and was ambushed and killed by Barbarians somewhere near Riverwood Hall currently sits. The primitive beings then took it west, into their camp in the Fangwood, where they were then eliminated by a band of Necromancers, who attempted to turn to their devices by enchanting with a spell that gave it the wrath of ice at night, but they failed, and and one of the relatives of Jason Angleo led a raid into their fortress (a 14,000 year old fortress from the ancient world, before the time of Karpath), slew them to the last man, and Jason's relative took the Crescent back to his compound in Nihon-Jan.
The Scythe is 7 feet long/tall, and blade is 4 feet wide/long. The blade, as the name suggests. It's date of forge is unknown, and is very likely that it fell from the sky, as the legend says.
At certain times during the day and night, it changes enchantments. During the day, it has holy magic and flame runes written into the blade, and during the night, it has ice runes and dark enchantments.