Hexbalde does not need even a single extra level to work with GWM and PAM.

It needs those levels for you to summon it. But you can still just use any normal heavy weapon (or Glaive).

And again, 1d6 is going against 2d6 and 1d12. Your comparison is just not a thing.

And your other comment is not true as well.

Extra attack is just expected.

The level 14 feature is actually mostly underpowered. It gets terribly outclassed by most of the Sorcerer’s level 14 features.

The level 18 feature is good. But that’s it. It’s level 18.

This subclass is 100% fine at any games.

It’s not OP for casuals.

And it’s not the best option for optimisers.

It’s genuinely really well made.