I finally got an ice axe attachment to fit into my crutch grip. I had a metal fabricator make a sleeve which fit a particular ice pick that I had that was made in the late 1980's. The Lowe Hummingbird tool. At the time it was state of the art. The reason this pick works so well for my application is that the part that connects to the axe handle is cylindrical, and I had a sleeve made that is press-fit onto the axe pick and then slides into the crutch grip which I then use a c clamp to hold it in place..

I thought it would be easy to get more of these Lowe Hummingbird picks on Ebay. Not so!

[...] I am trying to get 2 more picks. Here is a picture of it. I don't really care what the shape of the pick is, some are reverse droop or straight. It is only for self arrest and travel on neve. But it is cylindrical with a female threaded on the end for a bolt that would hold it in the axe handle.