Pulsed energy weapon
- "I will need the weapon back once your work here is completed. It is, after all, only on loan to you, temporarily."
While these weapons were significantly superior to traditional Goa'uld weapons and shields, lesser forms of Asgard weaponry are inferior to Ancient shields. Anubis was able to upgrade Goa'uld shields using Ancient knowledge he obtained as a result of his ascension, rendering Asgard weapons considerably less effective. It didn't take long for the Asgards to overcome that obstacle, however. Ori warships proved capable of withstanding weapons fire from an Asgard O'Neill-class ship. These weapons have, however, proven quite effective against Replicator ships which have just emerged from hyperspace, before their shields could be raised. (SG1: "Revelations", "New Order, Part 1", "Camelot")
The technology used in these weapons was a closely guarded secret by the Asgard as they declined to equip any Earth ship, though the Asgard scientist Kvasir also allowed the SGC to borrow an energy weapon after a string of alternate SG-1s began coming through the Stargate from parallel universes, but only after they promised to return it. The borrowed energy weapon was powerful enough to pierce quantum realities. (SG1: "Ripple Effect") These weapons were later rendered obsolete by the Asgard plasma beam weapon which is the weapon the Odyssey was equipped with when the Asgard upgraded the ship with weapons. Unlike the ion gun, the beam weapons were able to penetrate even the most powerful shields, including those of Ori warships and Aurora-class battleships although they were ineffective against the ZPM powered Hive Ship.
Although rendered "obsolete" by Asgard standards, Ion guns are very powerful indeed, far superior to any weapon of Tau'ri origin, and when properly powered more than a match for upgraded Goa'uld Ha'taks and most alien ships in both the Milky Way and Pegasus.