When it comes to getting equipment powered up quickly, map 2-1 is the best. However, later on, strengthening equipment gets a lot more expensive. That can be countered, somewhat, by running through one of the martial arts dungeons and strengthening equipment at the caravan. The farther you go into such a dungeon, the better the effect. Advanced seems to be easy enough to handle, has a high enemy density (which allows for equipment to burst along the way), and is generally simple enough, outside the toughies. This video just shows the use of zombies and the companion to get equipment to burst. Rakiel has 6 energy sources instead of 5 so he can burst equipment faster. Note how high the burst point limit is on the equipment I have and how quickly it bursts, especially the helms.

Toward the end, I encounter a glitch where the wrong music plays in the game. The last 30 seconds, however... click, click, clickity click! Line up 3 poison arrow traps right at the entrance, leading into the hallway, and just watch the zombies, and even the companion, press the button.