I agree that Antax is powerful and also think that BM needs a rework for single-target weapons. It just negates the real drawback so…
But i won´t say the chainaxe is bad. It´s just that you need to get used to it since it plays completely different compared to pretty much every other weapon.
Also yes, the heavy from Antax is strong, but i wouldn´t say it´s much better than the Antax on armored elites just because you get locked on the target.
If you´ve the freedom to do so, you can get a lot of damage out of a heavy with special in just one strike. If you don´t have the freedom you can still rely on light attacks. Not perfect, but they´re way faster in their execution and still deal good even with carapace.
(And that´s only based on basestats, no blessings imo.)