EDIT:

fat gripz will take the strain off your wrist while building grip strength at the same time.

the other thing you can do to strengthen the little muscles is an old boxers training drill for wrist strength: to scrunch up a broadsheet newspaper while sitting at a desk. Lay it open in front of you, float your hand to the middle of the page as if typing, and then scrunch up the page by keeping your hand in the middle and drawing the paper inwards scrunching up each page into a little ball. By the time you've done a few pages you'll feel it.

PS