On all my leather punches, I have started "dipping" them in beeswax before punching. Tools really like to get stuck in thick leather, and the beeswax makes it easier to removes and keeps them sharper longer. It also prevents bending tools because you don't have to wiggle and pry them out of the leather.
I have a chunk of beeswax I keep on my table, and before I punch something, I just dab the tool into the wax.
Ultimately, if you want the best stitching holes and uniformity, I would move to using quality pricking irons and a sharp/polished diamond awl. I got tired of hand stitching and bought a sewing machine. Hand stitching yields better results, but in the grand scheme of things, I don't think many people care about the difference between well done hand stitching and well done machine stitching.