The Ultimate Weapon is Panty's and Stocking's final and most powerful weapon, formed by combining a vast quantity of both panties and stockings. Their ultimate weapon was first featured in "Bitch Girls: 2 Bitch".
It seems their ultimate weapon must be 'authorized' by Judgement first before being used. Stocking asked for it to be authorized in order to defeat Corset and seal Hell's Gate. However, after forming the huge cannon-like gun and shooting it, their attack missed because they were holding it the other way around. The shot went straight to Heaven, causing Panty's and Stocking's mother to appear and squash both Corset and The Other Gods for them, sealing Hell's Gate in the process.
Full Ultimate Weapon