[quote]For example, when the wielder of this unique trait touches a sword, they will gain the knowledge of all who have wielded the sword, and knowledge of all battles that sword has taken part in, and the events leading to how the sword is where it is now.[/quote]

I personally don't find anything aside from this line a problem, but the problem it presents is... well, I dislike it greatly. I do have a suggestion. I know you have your Null Void blade, and I firmly understand that is the true purpose of the ability. Let's say we put a limit onto the trait that allows the user to gain the knowledge of "all those who have wielded the sword" to "all those with Jubin no Shindo who have wielded the sword" so that she gets the benefits from her Null Void blade or personal, familial artifacts, but can't just pick up a Warbringer Sword and learn about every battle from every user. A secondary edition to this would be "knowledge of all battles that sword has taken place in"; I don't mind that ability at all, if they're made into premonitions. She can study the past using the ability all she wants, but I don't want her instantly learning 'everything' about a centuries old item, and be able to use it. I would also add a function of difficulty for longer-ranging memories, e.g. memories from the Second Great Shinobi War would be easier to recall than memories from the First, and so on.

Do those editions sound reasonable to you, Ouroboros?