That certainly is a thug of an axe. Like Fraxinus says above, I would have guessed the same method of use, but that long handle does seem a big excessive. Perhaps that was a later addition making it a splitting axe after it got to the States?
Quite possibly, although my thinking, always a dangerous pastime :thinkerg:, is due to the curve of the bit in conjunction with the handle length the angle of attack would be a more angled slice across the grain. Which is more in keeping with the general school of thought with Japanese cutting tools, both for woodworking and Samurai katana's.
I don't recall seeing a Japanese axe with an offset handle, like you see on european or north american axes for the same purpose (side axe) some of which have felling axe length handles.
I'm no expert tho' just a C&J with an interest in tools of the trade.
Rob.