relationshipcrimes replied to your post: Hey actually what if Akechi literally couldn't...
like literally even if akechi knew about treasures as a concept or even a thing to steal, why would he think to send a calling card in the real world to make it manifest? you could know everything there is to know about palaces and how cognitions work, and nothing about that would even *hint* at the idea that a “treasure” mechanic exists, let alone how to use it
Oh yeah! I definitely think that expecting him to figure out how Treasures work all on his own in canon is pretty unreasonable. Igor straight up had to create Clippy-the-Cat to help Akira and the PT’s, but I also love the concept of Yaldabaoth manipulating Akechi to the point that he couldn’t have stolen the treasure even if he wanted to.
Maybe he made them invisible to his ward, or directly prevented them from manifesting in the palace, or somehow influenced their location? It’s wholly possible that he never even saw the weird oil-spill-on-reality form of a treasure because he doesn’t go looking for it, and the Thieves always encounter the palace ruler long before they lay eyes on their treasure.
Akechi seeing the Phantom Thieves in Okumura’s palace stealing something invisible to him? Standing in Niijima’s palace and not being able to see whatever it is that the others are planning to steal?
Or Akechi seeing a treasure for the first time in Okumura’s palace and realizing things could have been different had he known back then, or maybe would have known if he had only looked a little harder. But they weren’t, and what’s done is done. There’s only the one path left for him to take.