Combat (spartan style)

Looking for a way to do this myself but I don't see it. However I'm looking to increase the damage done by Mobs but at the same time I want the ability to attack with shield in the blocking state.

Eg. Think of Sparta 300 where they use their shields and attack at the same time.

There is a mod called Better combat in 1.10.2 that I used to use but now that I am in 1.12.2 I don't see it avail