I used to wrap the grip area with leather that was originally intended for bootlaces. The square cross-section was smooth enough not to cause blisters but under stress cants a bit and the edges grip back.

These come dyed with an orange dye that will stain your hands as soon as the leather gets wet or you sweat. I washed mine several times in water with a bit of mild detergent. I hung it to get the water out and wrapped it tightly around the grip area, with locking half-hitches every turn so it doesn't all fall off if cut, while it was still damp.

It lasted for quite a few years. Or at least until someone decided they liked my stick more than I did. Easy come. Easy go.