Well, that was completely unexpected.
So apparently, Zangetsu used those "shadows" to save Ichigo in the past, along with Blut, from what I can tell. This pretty much proves Kubo has been threading this theme throughout the entire story, and that's awesome. Additionally, he and Hollow Ichigo are "both Zangetsu". And as for what that means...
So, back in the real world, the forging of Ichigo's new Zanpakutō is complete, and we see yet another display of his power: he evaporated an entire goddamn ocean with his Reiatsu, which, of course, has never ever happened before. And now, Ichigo's new Zanpakutō is two blades, which remind me of Shunsui's blades, in that there's a shorter, likely faster one, and a long, likely stronger one. I do like the aesthetic of them, however: negative space looks nice. And since Nimaiya refers to them as "Zangetsus", apparently Ichigo is using both Zangetsu and Hollow Ichigo. That's, um, pretty balling. I also like the short flashback to his battle with the merged spirit, since that battle holds stead in a lot of the theories surrounding him. And it seems Ichigo finally understands, for Zangetsu "is [him]". OH DAYUM
And finally, back at the Vandenreich headquarters, Yhwach has some info to share...in the next chapter. Dat cliffhanger.
Anyway, another good chapter in my book. Kubo went in a very different direction from what I was expecting, giving us two different blades instead of the Buster Sword, and Ichigo grew just a little bit as a character, which hasn't happened in a long time.