[ As with most of the information that Sephiroth has uncovered, the physical needs of a shinki was pretty vague. Yes, they need to eat and sleep apparently, but that's about all he considers reliable in scale. But since he doesn't currently feel the need for either one of those things, he doesn't think too much on it.

None of that is as important as Zack asking for his advice and he gives the request serious consideration. ]

There are abilities besides the vessel name we're given that shinki possess. One of them is called 'borderline'. Since ayakashi can often be found when answering prayers, it would be prudent to test and learn these abilities beforehand.