"Well, he's been attacking the aliens with his death ray."
"It's a shame we don't have one."
- - Paris and Tuvok (VOY: "Bride of Chaotica!")
Doctor Chaotica's minions fire the death ray
"Death ray" was the term, popularized on Earth, which described the sort of weaponry possessed by potentially hostile aliens from other planets.
When Quark was stuck in 20th century Earth, he threatened to harm Nurse Faith Garland with his death ray. However, as Lieutenant General Rex Denning observed, "It looks like a finger to me." (DS9: "Little Green Men")
In Tom Paris' The Adventures of Captain Proton holo-programs, Doctor Chaotica had a death ray in his Fortress of Doom. In an accidental conflict between the holodeck characters and photonic lifeforms in 2375, the death ray in fact killed over fifty of the photonic aliens. (VOY: "Bride of Chaotica!")