Well, the Difficulty spike Hard gives you kinda dies out relatively soon. After getting past Thebel, going through Arqa felt like it did on Medium.

Even the Boss at the very top of Arqa is still a pain in the ass, though nothing a little Lamia with Survive light couldn't fix.

Also, for those who are having serious problems beating the Solo Boss at the first half of Arqa, Gurr works wonders against him.