Grandmaster (status)

Grandmaster (太宗匠, Daisōshō; literally meaning "Highest Master") refers to that have managed to surpass their limitations (限界, Genkai) within the field of combat. Within the, it carries a similar meaning in reference to those that attain the highest degree of mastery in a specific craft, but the title's importance is characterized much more within the spiritual realm. They are individuals that are regarded as having completely surpassed the existence of and  through their own merits.

Overview
The process of reaching the level of a Grandmaster is something that varies between spiritual beings and isn't something that can ever be taught. As himself has explained, the Grandmaster level is not something you "climb up to" but rather something you "fall into", suggesting that it deals with reaching some sort of personal epiphany. In other words, it is impossible to actually work up toward reaching this territory of skill and it is actually something that happens on its own when the conditions necessary for the ascension have been met.

While this is a status not exclusive to Shinigami only, as even Arrancar and other spiritual beings are capable of attaining the territory, the methods of fighting that are normally referred to when discussing the domain are commonly the Zankensoki: the four fields of combat that Shinigami typically utilize.

There are those that have accomplished similar feats and have broken through this proverbial hull by alternate means, such as Sōsuke Aizen using the powers of the Hōgyoku, which allowed him to evolve beyond the two-dimensional status of Shinigami and Hollow. However, despite this, it has been explained that Aizen had trapped himself upon doing so. No matter how strong he would become from this point on, he had reached his limit and would be unable to actually move beyond his status, which soon led to his utter defeat.