There are no exceptional throwing axes of any kind in our palette.
There was, however, a bug in the crafting database.
For most CNR items, the "Exceptional" result is the same as the non-exceptional result. For a few items, there is a different item that returns on an exceptional roll, but throwing axes are not one of them. That said, there was a typo in the database for copper, bronze and iron throwing axes for the exceptional result that referenced a non-existant item. The result is that an exceptional result returns...nothing.
I've corrected the database, so that an exceptional roll will return something, though it may not take full effect until the next server reset.