The berserk tier item varies from class to class, the Super Venter is a power up that lasts for the duration of the stage, so that one's intentional. The plasma gun being called the grenade launcher is a definite screw up on my part and it's something I've actually fixed for this big update I'm working on.
I should probably add a bit of text somewhere to tell the player if their current class has a permanent or temporary berserk upgrade.