The Lostvayne by Meliodas in Nanatsu no Taizai

The Lostvayne is the dagger (actually a sealed sword) used by Meliodas in Nanatsu no Taizai. It has the appearance of a broken and simple blade, but its power is unique: it allows the user to create clones, making combat more strategic. When released, it reveals its full form as a powerful sword.