The Sharp Dresser is a promotional weapon for those who pre-ordered the game "Assassin's Creed: Revelations". It is a replacement for the Spy's knife.
It is a hidden blade, similar to that of Altair Ibn-La'Ahad, Ezio Auditore da Firenze and Ratonhnhaké:ton. It has the same effects of the normal Butterfly Knife, other than not having the Butterfly Knife's taunt.