New weapons are primarily acquired in two ways: purchasing them from the Battle HQ using coins, or finding them in treasure chests scattered throughout the worlds. Each hero has a selection of weapons available for purchase, with more powerful options unlocking as you progress through the story. Treasure chests often contain unique weapon skins or more advanced versions of existing weapons. There is no traditional 'upgrade' system for individual weapons; instead, you purchase progressively stronger versions. Therefore, collecting coins is paramount. Always check the Battle HQ after completing a few missions to see if new, more powerful weapons are available for your team. Equipping the best available weapons for each character is a straightforward way to increase your team's overall damage output.
