A bag cutter for opening a sealed package using at least one of a blade and a piercer. Preferably, at least one blade is disposed partially within a cutout of an arm in a manner that exposes an edge of the blade. A piercer can comprise an extension of a cutout edge or be located on any other suitable portion of an arm. Another blade can be provided that is substantially perpendicular to the blade within a cutout, and juxtaposable against a cutting surface.