Just out of curiosity, what inspired you to make this thread? Got something planned? Brewing up a campaign?
I wish...sadly, it was just a review of the TV Tropes links for Known Space, and seeing all of the references to various ingenious weapons. It got me thinking about a variety of different "neat" concepts, and wondering if there were concepts that I would find novel after a lifetime of reading and watching sci-fi.
Dan Simmons Hyperion Cantos in one of the early novels has a multi-purpose assault weapon that manufactures a variety of ammunition or energy sources using nanotechnology. There were also starship mounted C-beams, and the Archangel class ships, which literally
killed the crew with each jump to FTL, then reassembled them using a combination mind recorder/parasite.
David Brin's Uplift books was an all-inclusive space opera where almost anything was possible, from psi bombs to hyperspace mines. In one book, an entire town of aliens is encased in a smothering gel of some type. Some weapons even altered the nature of local reality in unpredictable ways.
The webcomic Schlock Mercenary has weapons based on gravity manipulation, teleporting smart missiles, and large-bore handheld plasma cannons that make an
ominous hummmm.
The Nights Dawn series by Peter David featured AI-driven, antimatter powered combat drones, a supernova superweapon, cyborg mercenaries and a handheld device that would, for lack of a better description, erase your soul.
I've read or watch stories with people mangled, exploded, disintegrated, turned into technozombies, irradiated, ripped from the fabric of the universe, sent through or frozen in time, melted, and driven insane. Still, there has got to be an idea out there that is novel to me.