For those struggling with combat, there is a simple, but time-intensive solution.
Blackjack.
No, really.
The casino's variation of Blackjack has a huge player edge because the dealer never hits. If your hand total is not a bust value (22 or higher), and your hand total is 12 more than the dealer's face card, stand. You've won. (If you don't mind the occasional push/tie, stand when your hand total is 11 more than the dealer's face card.) Just be mindful that the casino's variation does not have aces; ones and elevens are separate cards. On the bright side, it is easy to save-scum. Grab a bunch of casino coins and head to the trading company to redeem the coins.
200 casino coins yields 20,000 gold. Any more than that ends up wasted for gold redeems. However, stockpiling tens of thousands of casino coins will allow you to get powerful weapons and gear like the Lucky Blade and an accessory that increases drop rates and luck.
After getting 20K gold from the trading company, head to the bookstore and start buying those books that permanently increase your combat stats. Each stat-increasing book has a 10-item limit, but those stat boosts, paired with the Lucky Blade, will allow you to steamroll through a majority of the monsters.