The interested reader may be wondering how these plasma weapons work, and why they’re running out of ammo. Well, they work by sublimating and magnetically braiding matter into a coherent plasma stream. The pack itself doesn’t actually store plasma, it converts whatever is in the pack into plasma for firing. It can convert anything, including atmosphere, but the more dense the input the more energetic the output. Running purely on air, plasma weapons are barely even lethal to unarmored, unengineered, normal squishy humans.
“Barely even” in this context meaning it’ll still kill a person pretty much instantly, it’ll just kill them a lot… less than usual. Keith or the Bender could probably survive for a couple of seconds unarmored.