The Exceptional Hardened Steel War Axe has a base damage of 47, penetration 0, durability 843.8. It can be crafted at level 56 and requires 16 hardened steel bars and 3 shaped wood to make.
The Exceptional Acheronian War-Axe has a base damage of 45, penetration 0, durability 843.8. It can only be crafted at level 60, and requires 16 hardened steel bars, one short handle, and 8 alchemical base to make.
There is no way this is intentional. The Acheronian Axe either needs at least +4 more damage, or at least some base armor penetration, given how incredibly much more it takes to make in materials.
Steps on how to reproduce issue:
Create a Blacksmith’s Bench (mine is Improved, if that matters).
Load it with the necessary materials and a tier 3 blacksmith (mine is Shemite).
It is possible that the boon for this weapon is in the stamina cost to wield it. I am not sure - I might be imagining things - but I could have sworn that the Acheronian spear drained less stamina per poke. Alas, I was not really scientific with this to be sure.
Still, I would tend to agree with you. More cost in mats ought to be worth something to the weapon to make it more desirable.
Not to mention that the model for the Hardened Steel War Axe is awesome in all the great details it has, and the acheronian one is not that great (if you put them side by side…) it almost looks like a cheap hatchet.