Mirror Man huh? Well Oner really didn't mind. It was sort of comical actually, not that it actually listed any chuckles from the Denizen, but it didn't bring a negative response either. "As interesting of a name as Mirror Man is, Joshua", Oner actually using his real name instead of some nick name like Reno always did, "It would be useful for you to know the signs so that you can tell which one of us is currently manifested." He now pointed at his jet black hair "If my hair is jet black like it is now, and my Spirit Veins are white", he then gestured to the white circle on his forehead and the white lines going down them, "then currently I am Oner. If our hair is pale white and the veins black, then Reno is the one who is manifested." 

It was a simple enough explanation on how to tell which of the two Keybladers were currently manifested, much simpler than what Reno would have probably given the other Keyblader, plus it would be good for the other two people here to know it as well if they were going to search for something together. Of course there was also the other sign as well that Oner acted and just felt much more mature than Reno did.