Most folks use their wrist when casting ... It's also true that many are not even aware of the wrist's action. For many like me, the snap of the wrist is the power stroke in casting. However, it's critically important that the wrist's movement be controlled within a very narrow angle. The following pictures depict the two positions of the wrist during the cast: the top is the decocked position ... it is the wrist's position that begins the backcast and stays in that position until you apply the power stroke at the end, and that snap places the wrist in the cocked position, shown at the bottom. The wrist retains this position until called upon to make the power stroke at the end of the forward cast.
To get a feel for this use of the wrist, grip a pencil as you would the fly rod and practice flicking the pencil between the two positions ... decocked/cocked/decocked/cocked. Note the pencil tip moves through a much greater arc then is your wrist ... If you stretch this to an 8 or 9-foot rod, you can see why this little flick is called the power stroke. This flick of the wrist really moves the rod's tip -- fast.
Be warned that either further movement of the wrist, or a failure to make that little snap, will ruin the cast ... I call it the floppy wrist syndrome.
If this is the problem your husband is referring too, I do recommend using Joan Wulff's Wristlok ... It's available from Cabela's for $11.95. It's worked well for my clients who suffered from the floppy wrist madady.
Hope this helps,