This paper presents the design and experimental evaluation of ASSIST-EW, which is a cable-driven motion-assisting device for the elbow and wrist. The development of ASSIST-EW was motivated by the need for affordable, effective, and sustainable assistive technologies that address rehabilitation and daily support for individuals with upper-limb impairments, with particular emphasis on elderly people. The design goals were shaped by considerations of the target population, clinical needs, and sustainable development objectives. The conceptual design was guided by an understanding of human upper-limb anatomy, including muscle actuation, joint degrees of freedom, and ranges of motion. These insights, combined with robotics engineering and cable technology, led to the creation of low-cost, user-friendly device configurations intended not only to deliver smooth, controlled motion during elbow and wrist exercise but also to be adaptable to different arm sizes. The devices were designed for both clinical and home use, promoting accessibility and extended usability. Experimental evaluations demonstrated that ASSIST-EW devices provided smooth, repeatable, and controlled motion assistance, validating their feasibility as a proof of concept and highlighting their potential as a practical rehabilitation solution.