Keep the Thunder Hammers damage, of course. At that point, we’ll be most of the way to one good weapon.
It’s pretty clear that the only reason the Thunder Hammer’s special has the awful kickback is so that the Crusher would have some semblance of an identity… Just scrap it.
With the awful “One page of chances at gear per hour” endgame system, every trash weapon you add is actively making the game worse. I can’t even ignore awful weapons as they’re taking the place of a chance at a good one. Adding the crusher in its current state is a slap in the face to your players.
They could make it a shock Maul and give it some sort of lighting effect that jumps between close enemies when powered up. That would make it distinct and let the thunder hammer have the explosion that it both should have and needs.
Alternatively make the thunder hammers special cleave through normal mobs like the power sword and let the big damage only go off on enemies of a certain type/mass. That way you can actually put that powered hit on the elite you wanted to hit with it and not some random pox walker that got in the way.
The maul is alright I definitely like it, but it definitely feels bad for it to get added when the thunder hammer is still feeling so unsatisfying.