Wood chopping You Tuber Nicole Coenen was gifted a spring-loaded axe by someone in her small town who knew she likes axes. She restored it a bit and put it to good use.
It seems like the leaves kinetically pop open and help kick the chunks of wood apart. Coenen replaces the spring that retracts them after each strike and claims the axe feels more alive than a standard single piece of metal axe. Spring-loaded splitting axes are still commonly available today if they look handy to you.
This video shows a cleaner, newer one and the mechanism is a bit more obvious.