There are many different recumbents suited to anything from really fast road burning to leisurely touring and two or three wheels. All of them will offer relief for your husbands wrists. I rode my Azub bike with one finger on the handlebars for mile after mile and my QNT needs no more than that to keep it on course while my Kettwiesel demands a light hand as a minimum controlling force. The difference between bikes is a lot more than the difference you can find in DF bikes.
You need to choose between 2 or three wheels, folding or non folding, hard shell or soft seat, underseat or above seat steering, (The latter has a wide choice of bars too!) angle of seat, (The more reclined you are the faster you will go.) and the relation of seat height to bottom bracket height.
A trip to DTek near Ely is well worth the effort. They have over 150 different recumbents in stock and a far better range than any other store. You can try before you buy and Kevin tends to discourage you from a hasty purchase until you are really sure of your needs. Call to make an appointment to ride and be aware Kevin spends a lot of time on the road, buying and delivering recumbents. He answers emails eventually so a telephone call is best.