Moras work fine for green saplings when you know to baton without killing or maiming yourself from a springboarding piece of wood. I've dropped more than a few trees of more than 8" which at first would seem impossible with a 6" blade. At that point a person is into dangerous territory, though.
They'll also split wood which splits easily - but tough wood is best left to a wooden wedge and baton as Chris says.. Once you get to sectioning up pieces of seasoned wood of more than 4", though, a knife and baton becomes a chore whereas a tiny hatchet or saw will get lots of wood sectioned in no time.
People might want to look at this thread on outdoors-magazine for some pictures of the actual tangs on various Moras. They vary greatly:
Tangs
I'm always amazed that my original old wood handled Mora is not only still in one piece but looks like outlasting me - despite LOTS of batonning.
Toward the bottom of this page are pics of me sectioning up a log with wooden wedges and baton made by a Vaughan mini hatchet. And that's not a cedar or pine. A Mora would have taken longer to make wedges, but it would have worked.
log splitting at bottom of page
One pic..
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