Hephaestus is the engineer of the Grecian patheon, and their principle researcher and inventor.
Goa’uld science and technology is particularly difficult for non-Goa’uld to learn, due to the important place that the element Naquadah and its less stable isotope Naquahdriah have in all the things they build and use. A metallic element supposedly found in the theorised Island of Stability, it is both dense, reactive, and also linked to the biology of Goa’uld. There is belief that it may also have been initially first formed at the time of the birth of the Goa’uld.
Hephaestus is particularly adept at designing concealment technology. he had a ring of observation satellites with heavy weapons platforms around Earth that had not been detected until 2008.