I agree Rick, and I suspect that the illustration are the product of the artists imaging of a 'pickaxe' drawn from assumption rather than an actual example. While it is exciting to see a period illustration, it is unlikely from an actual example, which seem pretty elusive.
I would think that for digging, the point would be wide across for penetrating and moving the soil. It is suggested that these were much like the trenching axes used by British forces in WWI, so maybe if we can find an example of one of those we might have some idea.
Thanks again Rick for coming in on this!
We'll keep looking
All the best,
Jim