I wish I knew how to split wood. I bought a few axes, but the body aches ain't worth it. My neighbor rented one for a tree, it was $105and a headache to get, cut the logs, then drop off.
I don't mind swinging and axe or splitting maul-- over the right kind of wood.
Wood that cracks and separates cleanly.
But when you're dealing with wood that's moist and flexible, and especially when you get to knots in the wood, that's where the blade of your manual tool will stick-in Get caught. THAT is when you appreciate a gasoline engine on a hydraulic log splitter.