Thunderstrike is a +1 Cold Iron Shock Heavy Mace that bestowes Electrical Resistance 10 on its weilder.
Found in the grasp of the evil Shar worshipping cleric Lady Arthras. Its origin is know only by few. Originally created by a worshipper of a relatively unknown demigod Thor. Although his clerics received their true spells granted by Talos, who bestowed these in a chance to secretly aquire more worshippers.
Belvedere Hornswoggle actually met the demigod in his travels through Chuult, where he was saved by the self proclaimed deity. Belvedere was so awed that he swore his oath to the large barbarian to worship him and lead his church to true glory. His first step was to create Thunderstrike, an awesome weapon to show his lord’s true greatness.
It was sometime later that Belvedere’s new church came into contact with a member of the chuch of Shar, Lady Arthras. She recognized the power in the minor artifact and set about slaying the Cleric of Thor.