GTW Akheton SDG
The SDG, or Subsystem Disruption Gun, is a tactical weapon developed by the Vasudans. Unlike other guns, the SDG does no hull damage at all: rather, it only destroys subsystems and turrets of the target. This has obvious utility in disarming or disabling operations. The SDG also does a moderate amount of shield damage to small craft. Howerver, the weapon's high energy requirements make it an undesirable choice for dogfighting.
If you're a pilot who likes to disable the turrets of enemy warships whenever the oppourtunity arises, even if it's not one of your assigned mission goals, you might wish to take the Akheton. In general however, there are plenty of other weapons that do the job just as well and have the additional advantage of causing some hull damage. Unless the mission specifically calls for a target to be disabled with minimal damage, one should leave the SDG at home.