W. Arthur Benson, the former president of Metallgesellschaft AG unit MG Refining &Marketing Inc and the man blamed for massive oil-trading losses that nearly toppled the German industrial giant, is suing his former employer and its main shareholder, Deutsche Bank, seeking $1 billion in damages for alleged defamation and civil conspiracy. Benson asserts in his suit that his efforts to staunch the losses were sabotaged by "byzantine maneuverings" designed to discredit former Metallgesellschaft Chairman Heinz Schimmelbusch, who was fired in Dec 1993