Does anyone know where to find the 4 pieces of the portrait for the frame in the Sage's archives? I have found three and am stumped on the last one
It's all over the Archives floors. One is in the small room to the left of the very first room, on the floor in the corner, the other I think is near the dark-haired woman on the spikes, the third one is somewhere in the dark vertically long area where one shinobi-type enemy stands, to the left of the first library, and the fourth one I don't remember. But they're all in this location so if you interact with all floor tiles you should be good.
Spoiler below.
Also you can open a path to the secluded cave somewhere there if you interact with a book in the first library. I don't remember which one tho.