As of the current state of Dual Universe (only 1 star system,) I think the idea of "Death Star" superweapons (or even city-destroying weapons) is out of proportion. However, I think that as the size of the map increases, and the amount of cities and celestial bodies increases as well, the idea of using some immense amount of resources to take out a city, space station, or even celestial body will make more sense. I think the best way to handle use of such weapons is similar to how EVE Online handles smartbombs and bubbles. When you are in "starter" systems, these weapons should not be able to be used. This way, starter planets and moons are not destroyed. However, as you get deeper and deeper out, you should be able to use these weapons, as the people you're fighting with are not newbies anymore. Of course, these weapons should require an immense amount of resources to construct and fire, and there should be a way to deflect or defend against these weapons. But I think if they require enough resources to use, they can become a non-overpowered part of the game.