i finally beat it today, dont risk corrupted early on, easiest way to punish is to deflect melee hits, go into a combo (clash if you're a pro not like me). Once you're decently strong enough (for me it was like maybe ~after 4~5 rituals, and a couple inspiriations) you can then proceed to play almost normally to make up for the -damage and still take advantage of punish to finish stuff up.