The Grenade Launcher is one of Max's left-hand weapons in Dark Cloud 2. It's only built up from the Trumpet Gun. As its name suggests, it's a grenade launcher: it'll fire at a slower rate than the semi-automatic pistols and the grenade will also fly slower than the bullets, but the grenades can be more powerful than the normal guns, depending to the enemy. You can find it in dungeons' chests, you can invent it, or you can buy from Gerald for 500 Gilda when he joins your party and when you get to the Chapter 3. It is a low-tier weapon (Tier 3), it'll gain 3 Synthesis Points (SP) after every level-up.