About the difficulty - it's a tiny bit disheartening to know that no matter what, Soma will never grow in power. Earlier portions of the game will never become easier to get through on subsequent attempts, unless something happens to change the geography like the Gergoth boss battle. I'm only up to the bit where you first see a Student Witch, using the guaranteed souls code because fuck grinding for them, and I have no desire to backtrack whatsoever, even though the hallway just above the Condemned Tower warp point is the best place to get healing items. I think the game would be better off in terms of a sense of progression if each boss gave you enough experience to level up at least once. That way, backtracking would become less of a pain, you would have more health to work with over time, and you can still carefully construct the difficulty however you please as you have been so far.
I'd also like to echo Aceearly in saying that the Valkyries are a bit strong for that early in the game. I get that you're designing this for insanedifficulty.com and not a casual gamer, but do keep the rest of us in mind, please.