Board Thread:Questions and Answers/@comment-5693502-20140409230628/@comment-8986886-20140410221931

I guess the primary reason why we never saw Ginjo use any Shinigami power, prior to his fight with Ichigo, is simply that we never saw him in his Soul form, aside from a flashback of when Ginjo first met Tsukishima. The interresting part is that Ginjo was able to use Getsuga Tensho and that Bankai form, while in his Human body, which is impossible under normal circumstances.

Another reason why Ginjo would keep his Shinigami power a secret, is that he told Ichigo that X-cution needed a Shinigami to free them of their Fullbring powers. If one of them was a Shinigami, they would've had no reason to ask Ichigo for help in the first place.