They may be a bit harder but the chainsaw will cut them. They needn't necessarily blunt the saw more except wood that has been lying around often gets contaminated with soil.
Bot good firewood, ash because it has a low moisture content when green and sycamore , whilst still having a low mc, dries fast when split.
No, some woods, particularly elm in the past, are harder to split dry.
I still prefer a felling axe, not sharp as that is more liable to stick but not badly blunt either. For awkward stuff I have a splitting axle with "wings" on the cheeks to widen the split. I find mauls and sledge hammer+wedge too heavy and will crosscut to smaller lengths to avoid having to use them. If it takes more than 3 axe blows I'll rip with a chainsaw.
Beech is best cut and split green it goes hard when dry. For splitting I use a splitting axe. One blow is normally all that is required. Wedges and grenades seem like a faff to me you have to get 'em started before you can whack 'em, simple just to have you wedge on the end of a stick. B-)
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.