If i ever encountered the stinger swords, i probably sold them (or if i couldnt in the act where i found them, in the act after where they converted to sellable stuff)
I cannot remember finding stinger swords, but then again.... i read the stats, not the name... there is no special quest for them, so i dont see any reason to keep them.
Yip, the alchemy material (there are various shapes and sizes through out the game), but they normally grey and squishy looking with "tentacles"
