Well, I'll try to give you some insight as much as I can but I'm afraid that if you don't like the raping theme and enjoy being challenged by a game then Karryn's prison might not be for you friend.Alright, the combat system is fantastic, and has a ton of depth. But that all gets thrown out the window when a random thug in the first room swings nearly all of your health in a triple attack. Seriously. So much potential lost to garbage rape fantasy. Karryn herself is great, and the actual gameplay is really fun, but the overall experience feels more cheap than playing old school dungeon crawlers because of this nonsense. I really want to like this game, but holy shit do I not care for rape, or the random fucking instaloss garbage. I got up to level 10, and a random level 7 goon can down me consistently. That's not good balance. Is Melty's Quest the same kind of raped all the time unfair garbage?
Now, about the combat... You level per your actions, so let's say you're always using that blunt skill, you'll level Strength. So you have to be careful when and how you fight depending on which kind of build you are going for. If you would like to go ''warrior style'' I suggest building more Dexterity as it allows you to hit and crit more easily. Also, maybe aiming for a +10 accessory might help you out. If you like the game and would like to steer away as much as possible from the raping mecanic, try playing on secretary mode. Enemies are easier and it is more forgiving. So in essence, levels are more an approximation or where you are compared to the level limit you have for each floor.
As far as the thugs are concerned, their special attacks can down you if you're not using the defensive skill to prevent that from happening. I don't remember where in the thread, but someone posted a very detailed walkthrough for many routes. If I stumble upon I will link it to you.
Now, about Melty's quest, you can avoid pretty much everything you want if you play on the easiest difficulty, but yes, raping is pretty standard in that game too if you play on the hardest difficulty available.
I hope this helped you. Take care.