Don't know anything about arthiritis or pinched nerve, but if you'll take one out of three, I do have the carpal-tunnel thingie (to use your technical term), and found that fountain pens are very useful for writing on paper, since they need much, much less pressure than ball points or gel pens or any of those modern "conveniences." Older (refurbished) fountain pens are even better, ones designed for the pre-ballpoint age, when the pens didn't risk being destroyed by people used to heavy penpressure. Even better, and I think more fun, and definitely cheaper, are dip pens (the kind you use with an inkwell). These are easily available at art-supply stores. Best of all are old dip pens, or at least the nibs, since they're designed for light pressure, like the foundtain pense. NOS (New Old Stock) nibs are fairly readily available for a buck or two each. PM me for more info, I guess, since it's more than a little off topic here.