I hear you on the green vs dry wood.
Obviously those axes that flew off were put on handles not so dry.
If I buy a handle I suppose I have to trust that it's made to the right size and won't shrink.
I'm sure the type of wood makes a big difference too.
We don't have native hardwoods good for handles here like hickory and ash. I planted american ash here some many years ago they are still no more than eight feet tall. Wouldn't make a handle if you took the whole tree, but the nice thing is so far animals don't eat them.
We had an old wood lathe going here for awhile, turned stuff from the forest both green and seasoned wood, so I've seen how the different woods will crack and shrink etc.
Also the common practice to seal the ends and let the wood dry slowly to minimize checking. I could see a wee toasting in the oven once it's completely 'completely' dry.
It's pretty damp here overall.
Spruce is a softwood but for the local woods it is the best to resist splitting, way better than even maple or cherry. It grew so slowly, the rings are very close together...you could turn it pretty green and never check. Roots are like that too, very dense. I bet I could find a handle sized piece in a pinch.