Hi Cathey,
A couple years ago, I created a thread depicting illustrations from the Nuremberg Chonicle.
http://www.vikingsword.com/vb/showth...ight=Chronicle
The very first post includes a depiction of Cain killing Able with an ax AND a depiction of Noah's ark being built. The artist(s) depicted what would have been in use in the late 1400s. The axe you post looks very similar to the woodworking axes. The off-set head further indicates carpentry as being its purpose (as has already been said).
Hope this helps,
-Rob