Resistances aren't a black-and-white issue I feel. Ichigo and Yhwach simply having "feats" of not being erased by point-blank proximity to Aizen isn't all there is unless you go into it without thinking about context at all.
When Aizen says this: "
Humans can't sense my power because they can't sense spirit energy. But their spirits are unable to withstand my power." That has an clear meaning to me:
Humans (AKA ordinary, non-spiritually-aware humans) are so "weak" spiritually that they can't sense spirit energy and they can't withstand Aizen's sheer power.
They're so much weaker, Aizen simply states "
Any human who comes into contact with me will cease to exist."
It's true, that Aizen could simply be saying humans because of the context that the only people around him are humans but the implication is still there in Aizen's words that even though
humans can't withstand his power, then other
things could. This is not to say that all non-humans can withstand his power. Nobody is demanding that Aizen say "Oh, and Hollows also can't withstand my power."
It's just a matter of there being a certain level of 'strength' that a spirit can be before it can withstand being near Aizen's power.
If Aizen had said "Anyone who comes into contact with me will cease to exist." or "Everyone who comes into contact with me will cease to exist." That would be different. That would most definitely imply that there is no upper limit to Aizen's ability here and that a difference in spiritual energy isn't a factor here. But that isn't the case, so that's why I don't think it is good to assume that Aizen's "hax" here is limitless.
Now, we get another mention of this "withstanding spiritual energy" here, for the Don scene: "
It seems you're unable to withstand my spiritual energy anymore."
This isn't Aizen flexing his Reiatsu in Don's direction. We saw that Aizen could do with that with a character like
Grimmjow earlier in the arc when he was much weaker. If he was actually trying to crush Don deliberately, he would have done so much sooner. So this is merely Aizen's passive spiritual energy, and Don (although incredibly weak in the grand scheme of things) is still able to stand within Aizen's range for a short period of time before being unable to withstand it.
So, we know that this passive ability that erases things is a result of Aizen's sheer power. He says as much when he states that humans can't withstand it, and he points out that his Reiatsu is undiminished and merely kept close to him when he erases a Shinigami. "
These restraints don't eliminate my spiritual pressure. They only keep it near me. I don't have to tell you what will happen if you try to touch me."
Taking this all together, the implications are clear. Somebody who is not monumentally weaker than Aizen will be able to withstand Aizen's sheer power / spiritual energy, and they would not be expected to be erased. When Ichgio grabbed Aizen by the face and dragged him off forcibly to a new location, Aizen was not surprised that Ichigo wasn't erased by him,
he was just surprised that he was physically overpowered. While it's possible Aizen was just holding himself back at this point, he still doesn't even think of trying to erase Ichigo, not does it cross his mind that Ichigo is somehow unable to be erased.
Likewise when fighting Yhwach, when Aizen has no reason to be holding back. He's able to physically interact with Yhwach and not erase him. Never is it implied that erasure should be happening and Yhwach is simply resisting it. It just never takes place in the first place, and is never indicated to be able to take place at all.
I rambled on a bit longer than I intended to when I started writing this, but I wanted this to serve as a sort of summary in case any of my earlier points were lost or misunderstood. Hope you can check this out.
@Agnaa @AKM sama @Arc7Kuroi
