Originally Posted by Wikipedia

The technological irony of the Lexx is apparent in its tremendously specialized function and organic body. An example of this is the complete and utter lack of a diversified weapons system, which is not common to most science fiction warships. Also, the Lexx has an incredibly soft exoskeleton, especially on the eyes, leaving it vulnerable to offensive attacks. The follies of Lexx's engineering are apparent throughout the series, mainly because it has no internal defenses or even a properly protected landing bay. The best that can be said for it throughout the entire show's run is that the bridge can be sealed. However, it is probable that His Divine Shadow purposefully made the Lexx weak in order to minimize the potential damage if it were ever captured by heretics: originally, the Lexx could not fire on ships belonging to the Cluster, and its planet-killer weapon could be easily predicted and dodged by sufficiently maneuverable ships anyway. Since His Divine Shadow had an entire fleet under his command to protect the vessel, this would not present a problem when it was used by him.