Really looking forward to these changes, especially heavy attacks and the return of blocking. What I'm not looking forward to is the return of 'melee toggling'. Cutting that out was one of the best parts of Phase 1, and bringing it back is totally unnecessary. I'm assuming it was added to facilitate manual blocking, but even though heavy attacks are taking the place of channeling (which would have been my first choice for a block key) there's still an empty key binding that would be perfect for blocking; the 'reload' key. It does nothing during melee, and mapping this as a block key could also enable blocking with guns simply by holding the reload key with a gun equipped.
Please consider doing this instead of the 'dedicated melee' system which only serves to slow combat and makes little sense with the new system.