User blog comment:Xilinoc/Ch. 540 - The Sword Five/@comment-8669536-20130605182414/@comment-4484409-20130607051333

@Ten Tailed Fox Yes the hollow is his Zanpakuto but the Hollow is not the prominent spirit in his inner world because his quincy powers have been the most dominant force. Yhwach!Zangetsu has just been imitating Shinigami powers. Therefore that cannot be a true Zanpakutoh because as Oetsu said only through his asauchi can a shinigami get a Zanpakuto. Ichigo's spirit weapon had some Zanpakuto qualities because of his inherited shinigami powers but it was ultimately not a true Zanpakuto. Some things that support this are the fact that Ichigo's weapon looks nothing like anyone else's Zanpakuto, the fact that he only ever had one attack while most other Zanpakutos with named attacks and not concepts/powers like Nigeki Kessatsu had more than one attack, and also the fact that the Asauchi deemed him unworthy.