[wmil]

This is really a specialty tool. Normal axes were also used to fell trees, demolish wood structures, and occasionally personal defense.

I'm guess that it's less useful if you're chopping against the grain or if you want precision.

[PeterisP]

Chopping firewood takes up so much labor, that there have always been specialised tools, there is no such thing as a "normal axe" - an axe for felling trees is different than an axe for splitting firewood, there are differences in the shape, width and weight of the axe head and you wouldn't want use one for other if you're doing it more than once a year; and a carpenter would use a different type of axe(s) than those.

And that's not a modern invention, it goes back for centuries. I'd guess that even stone age flint tools have been specialized in similar ways.

[ggchappell]

True. It's also worth nothing that axes intended as weapons are also very specialized. Indeed, there are multiple types, depending on just how you want to kill people with your axe.