Thread:Prodigy X/@comment-4992373-20131005080258/@comment-4992373-20131022235447

The zero in reiatsu talks about controlling it. Kenpachi doesn't control his energy consciouslly but sub-consciouslly.

Reiatsu basically being a physical force created by a person's Reiryoku, their actual energy. The physical force can also be used in combat if a person has control of it.

I guess it can also be described as a person's "waste" when using their "energy" but there are ways to make the "waste" useful, such as when Kenpach outputs so much energy he is coated in it, not only hardening his skin but also causing fear in opponents. Which is why I am slightly dissapointed when I see no one has anything about their control on Reiatsu when there is so much you can use it for, other then Kido.

As for an idea on what he created. I don't recall if anyone actually invented it personally but you could try the Kaikyō Kotei (界境固定, Realm Boundary Fixation), the technique used to stop the floading walls of the Dangai, which is actually pretty useful.

I did make that a main reason though as to make Takashi a Hand-to-Hand master though, as he is willing to sacrifice an arm or leg if its to protect his zanpaktou from breaking.