For any gardener with problems in the hands, whether it be arthritis, rheumatisim, carpal tunnel syndrome,or even general weakness of the hands, it may be good news to know that specialty tools are available to help you.
One classification of such hand tools are the ones that have been totally redesigned from the standard tool yet still allow the function to remain.
The Handform Trowel and Fork by Hubbard Yonkers feature a curved handle which allows the best positioning of the wrist while providing maximum leverage.
There is also the Corona Comfort Line that features larger, cushioned grips.
You can also modify your existing tools by adding your own padding on the handles. You can wrap and glue foam rubber. You can purchase long lengths of rubber tubing and cut it to size and secure well. Even heavy duty tapes can be wrapped to an adequate thickness.
Another consideration is cushioning your hands themselves as well as the tools.
Wheelchair cuffs can be quite useful for the non-wheelchair user. These are made of suede leather and are designed with open fingers and thumb yet still protect the hands and wrists.
Also, you might consider a visit to your local bicycle shop to try on fingerless, leather palmed bike gloves that are usually lightweight and durable.
Adaptive Gardening Equipment by Julia Beems gives detailed info on how to make homemade forearm cuffs for gardeners who need extra help holding a tool in the hand.