Masō-Shōjo (魔装少女?, lit. "Magical Garment Girl")
While digging for gems outside Ponyville, Rarity comes across a broken object with a strange incantation on it's surface. Upon reading it, Rarity gains a cute and sexy ensemble as well as immense strength, agility, and a brutal looking weapon. With these powers Rarity will become a brutal hero of justice and look fabulous while doing it!
(Part of a project i call, Garment Mares of Equestria.)
(Just a one-shot. Might make more of em later. Hell, make some of yer own. THAT i would like to read!)