The Lava/Meteor gun in Ratchet and Clank 2 - It starts off as a Lava Gun which lets you have lots of fun spraying hot sticky death over everything in sight, And then when it upgrades, it suddenly becomes a terrible, low range meteor gun that flings low-damage meteors. At least they got it right in RAC3 - It becomes better and better lava, then when it maxes out, it suddenly becomes the polar opposite of lava - Liquid Nitrogen. Still behaves in the same way, but does far more damage and freezes stuff. Nice.