The Thunder staff is a version of the standard Jaffa staff weapon modified by scientists and warriors in service to the Goa'uld Raiden. It was modified by Raiden's people in laboratories in the capital city of the planet Kyoto, and used by Raiden's Thunder Guard.
It has two modes of fire; the standard blast of a staff weapon, and a thunder mode which adds a sonic blast to the standard staff blast. The sonic blast is capable of deafening and stunning its target, but the thunder mode can only be fired every 3 shots. (RPG: "Fantastic Frontiers: Stargate Season One")