Unlike Psaro, your monster companions can equip weapons and armor to boost their stats. Weapons primarily increase a monster's Attack stat, while armor boosts Defense and sometimes other stats like HP or Agility. Each monster type has specific equipment they can wear, so not all items are universally usable. You can check a monster's equipable items in the Party menu.

Equipment can be found in treasure chests, dropped by defeated monsters, or purchased from merchants. Pay attention to the stat bonuses provided by each piece of equipment. Sometimes, a weapon with a slightly lower Attack stat might be preferable if it offers a significant boost to Agility or a resistance to a common elemental attack. Regularly upgrade your monsters' equipment as you progress through the game to keep them competitive. Some rare equipment might even have special properties or grant unique skills.
Compare weapons & armor inDragon Quest Builders 2