User blog comment:IceBite/Kklxin's Last Superweapon/@comment-1743498-20120507231500

I actually have an old sequence of King Rustiagon Karrel sabotaging a Harbinger superweapon which is much the same as that. Since I plan to retcon the story anyway, I guess we can recycle some earlier ideas:

The Star Buster. It fires a gigantic missile that is capable of withstanding both the intense gravity and heat of a star. When it reaches the center, it acclerates the sun's life cycle causing it to go supernova and destroy any planets in the system.

As for this history, here's a few ideas:

The Kklxin used to have a bunch of these in the past. They were just ordinary ships to their standards. But with their galaxy destroyed, the ships perished as well so they needed to construct a new one from scartch using whatever technology they had left.