If you describe a system as unwieldy, you mean that it does not work very well as a result of it being too large or badly organized. His firm must contend with the unwieldy Russian bureaucracy. an unwieldy legal system. = cumbersome
lacking grace in movement or posture; "a gawky lad with long ungainly legs"; "clumsy fingers"; "what an ungainly creature a giraffe is"; "heaved his unwieldy figure out of his chair"
If you describe an object as unwieldy, you mean that it is difficult to move or carry because it is so big or heavy. They came panting up to his door with their unwieldy baggage. = awkward
difficult to use or handle or manage because of size or weight or shape; "we set about towing the unwieldy structure into the shelter"; "almost dropped the unwieldy parcel"