The Lightning 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 Lightning Guard.
It has two modes of fire; the standard blast of a staff weapon, and a lightning mode in which the blast appears to be a bolt of lightning. The lightning bolt is capable of stunning its target, but the can only be fired every 4 shots. (RPG: "Fantastic Frontiers: Stargate Season One")