Damasko and Heikki does ring a bell! Honestly, I think Damasko will be fine fighting jellyfish. Keto attacked one bare-handed at age five being a stupid wannabehunterkid. I put a shark skin shirt in his inventory for armor. The key is that if your health gets in yellow or orange, to disengage.
I know, I learnt it when I fought with my two-metres feline against a parrot in an epic battle... and had to disengage. Was like, WTF?