Farming 400+ DMG Weapons - Ni No Kuni 2
Edit:
Make sure you have armor sets with the bountiful or bootyful prefix, as they increase equipment drop rate. The Lucky Locket, or the Extra Lucky Locket also helps a lot. With the 3 party members equipped, if you have all Bootyful gear/ Extra Lucky Locket equipped, and a Level 2 Tactic Tweaker for equipment, i have found it to drop me treasure about 90%-95% of the time.
End game grinding for strong weapons if you don't want to forge them. I averaged about a 70%-80% drop rate on Weapon Chest after equipping all the proper gear, and with a level 2 tactic tweaker for weapons.