I've just been told that in the final battle with Corypheus, he yells at a still-vallaslined Lavellan:
"Look at you! Wearing slave markings on your face with pride!"
This implies that the time of the First Blight, even humans knew that vallaslin were slave markings. Whether this is relevant I don't really know, but I wanted to point it out. ...And it proves Solas was telling us the truth about that at least.
And on a side note, according to the wiki:
"Defeating Corypheus earns the player the achievement "Conductor". Classical Greek κορυφαῖος (koryphaîos) means "conductor of the chorus", possibly explaining the achievement's title."
We know from that lovely codex entry that I can only vaguely remember (sorry - the one written by Corypheus' slave, who sent his family away to avoid being sacrificed to fuel a blood magic ritual) that Corypheus chose his name himself. I find the selection interesting, seeing as the Blight/the Calling/lyrium/Archdemons emit a "song". Does his choice of name have any meaning for the lore, I wonder, or was it just a way for Bioware to pick his name?