The appropriate functionality of the human shoulder including the shoulder girdle movements is crucial for effective use of the arm during activities of daily living (ADL). It is important to assist all shoulder degrees-of-freedom (DOFs) when implementing robotic exoskeletons for rehabilitation purposes to increase the range of motion (ROM) and avoid any joint axes misalignments between the robot and human's shoulder that cause discomfort to the user. In this paper, a new lightweight shoulder exoskeleton is proposed, which can provide anatomically accurate shoulder movements to the neurologically impaired subjects by assisting all of the human shoulder DOFs and can minimize any effect of joint axes misalignments. The description and operation of this hybrid multi-joint ergonomic mechanism is presented in detail. Its kinematics, preliminary workspace analysis and mechanical interference issues are examined using CAD software tools. The discussion and future work on the proposed robotic shoulder exoskeleton are given to indicate its benefits of larger workspace, intrinsic compliance and increased functionality.