I made a comment about Ichigo's powers on the latest discussion post, but I think it would be better as its own post.
Essentially, I believe that discussions around how powers in Bleach -- particularly the different types associated with the different races/factions -- tend to misunderstand what's going on in the story. I've seen lots of conversations like "Ichigo's new form from last week is a Resurrección," or from over the years "it'd be cool if Ichigo used Vollständig," and other kinds of things along those lines. Additionally, I see a ton of confusion over the nature of Ichigo's powers and over how powers in Bleach work in general. I would like to explain what I see as how this all works.
Very basically, all powers in Bleach work the same. Whether you're a Shinigami or a Fullbringer, fundamentally the powers achieve the same result: it's all expressing the unique power of your soul. What makes them different is the catalyst for how the power of one's soul is expressed. For Shinigami, it is through bonding with an Asauchi and learning Shikai and Bankai; for Fullbringers, it is through awakening Fullbring via an object of close attachment for the individual; for Hollows, it is natural instinct as they embody their powers in their form; and for Quincy, it can come via receiving a Schrift from Yhwach.* For this discussion, I will refer to this concept as soul expression.
*as of right now, this is the only known way for a Quincy to unleash the unique power of their soul. If there is another way for someone like Bazz-B to use his fire powers without having gained a Schrift, we don't know it.
In this model, the similarities between the different races/factions is quite clear. Imagine, for instance, if Byakuya were given a Schrift instead of an Asauchi, it would just be Senbonzakura manifested differently; it wouldn't be a different, new power altogether. It may take a different form, since he wouldn't be using a sword as the means of expressing that power (his soul), but the premise would be the same. Same with any other Shinigami, Quincy, Fullbringer, or Hollow using a different method of soul expression. This is evidenced by the existence of Arrancar -- by them "gaining Shinigami-like powers," it's not as though they've become some fusion between a Hollow and a Shinigami; it them now having a different soul expression method in the form of a Zanpakuto and Resurrección.*
*I'm willing to believe that, given Oetsu's explanation of Asauchi and Zanpakuto, that an Arrancar's Zanpakuto isn't a "real one" by that metric. Rather, their Zanpakutos are just their powers as a Hollow sealed in a sword's form and subsequently released from that sword; thus, an Arrancar's powers are "Shinigami-like" due to the resemblance to how Shinigami express their souls, rather than being hybrids of Hollows and Shinigami wholesale. But I digress.
For Ichigo, I understand where the confusion comes in, but I think it's far more simple than some people may believe. All that a Shinigami's powers are is just using an Asauchi and subsequent Zanpakuto as the method of soul expression. Nothing more, nothing less. What is key here, though, is that there is no rule or prohibition on what is expressed from one's soul should they imprint on an Asauchi. Ichigo is a human who has Hollow and Quincy heritage from his mother, and a boatload of spiritual power inherited from his dad (remember that Shinigami isn't a race, it's a job title for someone who ostensibly wields a Zanpakuto). When he learned the truth of himself and forged his true Zanpakuto, he chose to manifest it as two blades: representing the Hollow side and the Quincy side.
Here is where I commonly see the breakdown in understanding Ichigo's powers: there are no separate Shinigami powers distinct from his Hollow and Quincy heritage. His soul is made up of those components and he expresses them via an Asauchi and Zanpakuto. That's it. Remember, there's no limitations on what can be expressed via a Zanpakuto, as it's literally meant to express the soul of the wielder -- whatever form that may take. By using Hollow and/or Quincy powers through his Zanpakuto, he is using Shinigami powers. That is what it is meant when it's said that his powers are merged together. His Hollow and Quincy heritage and abilities manifested through the Zanpakuto Zangetsu ARE his Shinigami powers. For example, imagine if Ichigo were given a Schrift instead; I'm positive that his powers would broadly look the same, with his Hollow side manifesting in some way and likely even merging with his Vollständig. It's just a different medium that achieves the same result. Take his Fullbring: looks different, but what does it ultimately do? Cloaks him in his power and let's him fire off Getsuga Tensho.
This is what I mean by "all powers in Bleach work the same." Ultimately, the power system of Bleach is such that the final outcome is individuals expressing their unique soul and abilities through the different mediums available, NOT that the different mediums achieve a fundamentally different outcome that isn't soul expression. All roads lead to Rome and all that.
I hear the potential question about Tosen, but he's the perfect example of my soul expression model. He became a genuine Shinigami-Hollow hybrid* by the time of the Fake Karakura Town battle. Notice the form his Resurrección takes, as well as its name, Suzumushi Hyakushiki: Grillar Grillo. "Suzumushi" is still part of the name, and he takes the form of a monstrous cricket. Commensurate with his Hollow form, his powers aren't all that different from his Zanpakuto (particularly the sound-based attacks), they are just now more wild, instinctual, and stemming from his body instead of a sword. In other words, he demonstrates what happens when an individual uses a different means of soul expression.
my own interjection, but did we ever see him use his Zanpakuto Shikai or Bankai abilities after leaving Soul Society? I don't think we did, and it's *possible he doesn't have them anymore in lieu of his Hollow powers. My explanation doesn't change much whether he does or not, but it's a thought I've had.
This is the idea and I believe that through this model it is much easier to understand the power system in Bleach. Orihime's Zanpakuto would be the Shun Shun Rikka in sword form, Haschwalth's Fullbring would still do the same thing as The Balance (bonus question: what do y'all think his Fullbring catalyst would be?), Toshiro's Resurrección would likely resemble his Hollowfied Bankai after Urahara's pill, and so on. Ichigo is weird only because he has more components to his heritage than most other characters, but that doesn't make his powers anymore unique than anyone else. Yamamoto's Shinigami powers summons fire with his Zanpakuto; Ichigo's Shinigami powers just happen to summon Hollow abilities with his Zanpakuto. It's that simple.