I can get what you're saying, Pend. And it is a very understandable argument.<br/><br/>yet, by the wiki article, it says that any Flagship Battleship, or Super battleship "Could" possess it. That does not necessarily mean they "Do" possess it. So far, as far as I can tell. The Mirror Ring has only been seen/used twice. Once in the manga, and once in the Series. As for why U-2501 has it, that is something that I hope the Manga would explain. Even so, Yamato ordered Takao's memories locked after her defeat by it. Probably to keep it secret. And don't forget, it is a double edged sword as well as it destroys friend, and Foe, or at the very least severely damages them. Probably which explains why Hiei had her Cruisers come very close to her. To minimize the damage to them, and use them as a shield while she is weakened.<br/><br/>So while they have potential to be overly used, So far the Franchise has been scarce on its implementation.