I don't think the fair & square luck mode difficulty is way too much, even the basic unarmed punch can take out good enough chunks of enemy HP while the game calls a critical hit under the luck mode LCK 99+20 (+20 comes from the Lapis Lazuli brought out by luck mode start) boost. Whether or not call a critical hit is random - RNG based but beating the game shouldn't be problem with better armor equipment and tiny little bits of luck