It'd be nice if there were some skill-based way to block crush through, besides a chamber. Aiming a shield up, for instance (thus exposing your legs and feet.)
I've found sidestepping works pretty well against big overhand weapons in all but tight confines. If that's the case and you're against an opponent wielding a crush through weapon in a narrow alley, you're in their prime territory I'm afraid. It's like facing a cav in the open, or an archer who is on a hill and you've got no shield. Find some way to get them out in the open, or die.