I understand that monster difficulty ratings change based upon my Hero's stats; a monster who was normal five levels ago is likely easy or very easy now due to how I have improved my player.
How about monsters just having a flat difficulty, instead of it being related to your Hero's stats? Something with a Level 1 difficulty rating would be pretty easy, the kind of thing you take on at the beginning of the game (rats, forest wasps, black ants, etc.). As the difficulty of the monster increases, so does their difficulty level. Oskar has developed a system for calculating the cost of a weapon based upon it's statistics, and this would be a similar concept. If you wanted to take it to the next level, a player's stats could also show something related to monster difficulty, like Very Easy 1-4, Easy 4-6, Normal 6-10. How each difficulty level relates to that player would change based on the Hero's stats.
Just an idea for something else, as if the awesome developers don't have enough ideas to consider.
And, thanks for taking the time to develop this game and to actually integrate player feedback into the development. Totally awesome!!