Finished IMO Josephine was harder than the demon of lies
Yeah I had the same problem. In the end, my character was able to walk up to the Demon and simply hack away and soak up the damage of both the Demon and his pets (inculding his 'duplicate'), with a few Restorations taking care of healing. By the time the Demon fell, six or more bad'uns were hacking away at me, while I stood in the middle of a conflagration, and I didn't even notice. Josephina was a pest though. Rotten 'Blind'-spells!