Except she isn't.
Xianghua at least managed to maintain some originality for a while as the first cute happy girl of the franchise (the closest thing the series had was Sophitia, but she was more of a serious and heroic instead of happy).
Setsuka, on the other hand, was introduced as a badass japanese woman who is a rival to Mitsurugi... EXACTLY LIKE TAKI. The thing is that Taki was older and had interactions with other characters, not to mention she actually was connected to Soul Edge. Setsuka was only related to Mitsurugi and no one else, and didn't even care about neither Soul Edge nor Soul Calibur. The only other relationship Setsuka got was being the master of Patroklos in SC5 (she got nothing in SC4), and, if it wasn't enough that her very name took time to be mentioned in that regard, the style she taught Patroklos is not even his main one in the game. At least Natsu was specifically tied to Taki and made it obvious in her fighting style. People complain about Natsu, but Setsuka is the true Taki-turned-to-shit, she is irrelevant and redundant.