Structured walking practice is very important. The more walking, the better. Preparing meals to be served in a room several rooms away from the bedroom encourages walking. Or having meals outdoors during the summer. There is a technique to walking with a cane and a walker and using the various aides to help a person dress and undress. Make sure the physical rehab specialist explains these things.
A rehabilitation specialist is a good idea. The thing to do is to watch the specialist and ask them to teach you the rehabilitative techniques to leverage their presence. Some of the will flat out refuse to do so, curiously enough. If so, don't get mad. Get another specdialist. You won't have enough money to hire a specialist to perform all the therapy needed, and it can be enjoyable and rewarding to do this yourself, especially if there is visible progress. Many of the techniques are relatively simple. It's not rocket ship science.
You also might try rubbing an ice cube up and down his paralyzed arm down to the fingers two or three times a day. Ask if he has sensation when you do so. You are stimulating receptor sites when you do so.
I might add I have rehabed a stroke damaged 101 year old woman who was essentially totally paralyzed and unable to speak or move. Two weeks ago she magically regained totaly motor control of her hands, and is not only able to feed herself, but she can peel a bannana, handle a cracker, gesture, and this was a person unable to hold a spoon a year ago that everyone had given up on. She has regained the full range of facial expressions and laughs and laughs all day long. She was treated by the best stroke rehab specialists in the country who said there was no hope. It takes patience and love, but brain function can be restored.
The problem is that rehab specialists are expensive, and they really don't give a damn. You can learn the rehab skills yourself. The thing to always remember is that behind that person who doesn't seem to respond is a normal functioning brain, and don't let them tell you otherwise. Have patience and use a lot of stimulation. Allow the patient to watch lots of television with an earpiece so they can hear the material, as well as get verbal stimulation. While they are up they should always have aural and visual stimulation. Probably they have the patient on coumadin. They do this, and it reflects the standard of care, but there is a tremendous downside for the patient. Their abiloity to enjoy normal foods, a great pleasure is totally destroyed. And with the coumadin come inevitable brain bleeds. Mother nature doesn't do nothin for nothing. Clotting factors were put there by the life-force for a reason. Going off the coumadin is a big decision and your doctor won't back you up. If you do so, you need to insure that the patient is properly hydrated with a hydration log. Lack of hydration produces clots. And exercise to the limit of possibility. And you need to ensure they take in substances such as daily cod liver oil. Vitamin C in high doses is contraindicated, because it is a diuretic, and will increase the probability of a clot, IF you don't maintain hydration. If you watch and maintain hydration, high C is fine, but don't do one without the other. Stimulation, stimulation, stimulation. Take him outside every day, expose him to sunlight for at least 45 minute every day, and expose him to the world, treating him like a sentient human being, which he is. Reemember the vet adage: "What doesn't move dies". Don't give up on him. Feed him attractively prepared soft stroke friendly foods. Throw away the ensure. And pray.