Forget about weapons, about armors, about accesories: well, you do need them for very early game, but once you reach World of Death you have efectively beat the game. As soon as you're able to buy at the WoD stores, SELL EVERYTHING FOR SOULS and buy... books.
No, really. They are +5 Attack / Defense / whatever , at 50 souls each. Buying 180 of them (enough to permanently pump the MC attack by 900) costs 9000 souls - less than any 10000-souls sword that gives only 110 Attack. Pumping to 999 his attack, defence AND magic defence (so he deals thousands of points and always gets zero) costs less than a single 30000 sword. And as soon as you're halfway into that pumping, you can pwn the catacombs like a natural disaster to get in a few minutes of IRL gameplay enough souls to pump EVERY stat of EVERY party member to 999. From there, all those "I can't beat this foe" battles are a matter of selecting "fight" and leaving the finger pressed over "enter".
I call this exploit "the book is more powerful than the sword".