Difficulty_MonsterLuck is the modifier added to the monsters' attacks. When editing a variable, make sure to press the button "SET" which appears all the way on the right of the variable. If, despite that, you still get easily killed try "Normal difficulty" since not all variables are exposed in there, changing difficulty mid-game is not really a thing.
Also, make sure to never be ill equipped, the game used to be easier during R35 or before because some items and features were missing, now the game has been rebalanced with the expectation that you'll always have a few potions, morbuls, smoke balls, etc.