Add chip damage. Chip damage would make people go for parry and not just block everything. The damage would be like 20-25% of an attack. This is not so big to complain and not that small to be turtle. Like a raider heavy(which is the most damage in the game equal to shugoki heavy) would hit like 9-10 damage which I say again is the biggest damage in the game from a heavy. It would make people to go for parry and assassins to use deflect ability. And you would start to worry that PK would be so OP cause she could spam light and do so much damage but she would not. Her lights are not doing that much damage and the 20-25% of that damage would not do big damage.
And the second part of the solution is gb should only interrupt an attack if you feint it. If you want to feint an attack you have to press the feint button almost inmediatly so if you dont ffeint it, it should not interrupt the attack.