When it is your turn, press space to begin attacking, and press 'A' at the right time to deal 2 damage instead of 1. When the enemy goes after you, press 'A' at the right time to block their attack and only take 1 damage instead of 2.
The demo for my massive project is imminent! In the meantime, I'm uploading this project I made about a year ago testing out a Paper Mario style action command system.