Legendary Weapon: In the Empire, the thing about most legendary weapons is that they tend to stay legendary… due to not staying the same weapon, or rather, the same embodiment of the weapon.
Aorillia, the Sword of Illimitable Light, for example, the legendary weapon of the champions of the Solar Empire, has over the course of its history been three swords, two sniper rifles, a man-portable laser, three different battleships (one wet, two space) and a dreadnought. (Many of the earlier examples of which are, indeed in display cases in museums.) But they share the name of the legendary weapon, and theologically speaking, they share the essential spirit of the weapon – and so for all mythographic intents and purposes are fundamentally the same weapon even if their materials forms and capacities are obviously not.
And since the mythographic truth is the important thing when it comes to a legend, thus it is.