In Earth Defense Force: Insect Armageddon for the PS3 and Xbox 360, you can unlock the most powerful weapons in the game by ranking up certain armor types. These require reaching rank 8, which can only be done in Inferno difficulty. Once they’re unlocked, they’ll show up as a free purchase in the deployment screen.
Pesticide Cannon (Tier 8 Rocket Launcher) – Get rank 8 with the Trooper Armor
Pesticide Missile (Tier 8 Missile Launcher) – Get rank 8 with the Tactical Armor
Pesticide Mortar (Tier 8 Grenade Launcher) – Get rank 8 with the Battle Armor
Pesticide Rifle (Tier 8 Sniper Rifle) – Get rank 8 with the Jet Armor