Ion Weapon technology was originally acquired by the the Tau as part of a fruitful alliance between the Syrr'Tok Brotherhood of the Demiurg and the Water Caste of the Dal'yth Sept. However, despite the eventual widespread dissemination of Ion Weapons during the Tau Empire's Second Sphere Expansion, man-portable Ion Weapons remained an impossibility due to the bulkiness of their power sources. It was only the discovery of a Mor'tonium power source during the Third Sphere Expansion that made the efficient powering of small-scale Tau Ion Weapons possible.