Isolde had tried to kill him with a sword , but when Tristan had looked into her eyes her heart had become full of love and she had dropped the sword . Isolde attempted to kill the man with his own sword as he lay helpless before her . However , Tristan looked not at the sword that would kill him or the hand that wielded the sword , but into her eyes ( `` Er sah ' mir in die Augen '' ) .