Thread:Mangetsu20/@comment-18812574-20140201220349/@comment-4326112-20140202071414

Don't do the Reversion Idea. I feel like its a convoluted and contrived one, sorry if that seems harsh. Rebuilding a Zanpakutou, for an Arrancar, is like them rebuilding part of themselves. They didn't create themselves and certainly didn't create Hollows, so how could they preform such a feat?

Honestly, devouring Hollows and physically training with their released state and their sealed sword is the only manner in which I believe is the most feasible and Canonical manner for them to reach a state within eventuality. Unless you take the full mask ripping theory I suggested (which, for Numeros, would most likely be lethal) the only thing I can suggest is that there was a Natural Born Arrancar somewhere out there in the wilderness that Aizen managed to overlook. If you remember, the natural born Arrancars were uncommon but not rare, and only the Vasto Lordes seemed to be in rarity and desired by AIzen in his army

Ulquiorra is the only known confirmed Vasto Lorde, just to let you know how rare they are (Starrk was an odd duck, and Barragarn with Harribel just seemed like Elite Adjuchas-class Hollows)