Re: chronic wrist pain
It is usually pretty straightforward to see osteoarthritis on a simple xray. Also called degenerative joint disease, or DJD, it means that the cartilage has worn away from the ends of the bones, there is excess space between joints, maybe some calcification/bone spurs growing. If no xrays have been done, I strongly recommend getting a doctor who will order them.
In addition to what John Riggs suggests, some folks find relief with capsaicin based topical ointments/creams; apparently the regular use of this overwhelms the sensory nerves and over time may actually keep them from firing. It is NOT a good idea to use it on a new, acute injury because you need the sensory nerves to give you feedback on pain so you let it rest and heal. The thinking is that on osteoarthritis the pain is essentially chronic, longterm and you need to cope with it to get on living...
Having said that, obviously you don't want to keep heavy cranking/use that will make the joint damage progress even faster! A combo of exercise and rest is usually suggested, but each of us needs to figure out how this applies to ourself.
The problem with wrists is that there is very little muscle to develop to strenghten them, mostly the wrist is bone and tendon. I agree with the poster who suggested weapons; if you can tolerate doing suburi or kata w/o pain, doing it to the point where it hasn't hurt yet and doing it regularly sure would help.
In terms of training, can you suggest folks do alternate techniques (like applying sankyo to the fingertips or kotegaishe to your forearm)?