So, there is some uncertainty in the book when Talarius is scanning the “Palace of Evil” with his mirror.
He sees 4 dots of interest. He sees one green one running around and 3 blue ones. Two of the blue ones are close together and one of the blue ones is light blue, perhaps slightly turquoise.
First, the missing information: is the light one the one on its own, or is it with one of the dark blue ones?
Now onto the fun analysis. Obviously the two standing together are Ramses and Exador. We know that around this time they are conversing. The other arch demon in play is Bess so she must be the other dot. The green one of course is a Level 4 and therefore Tom. But we later see that Rupert registers as green and we know he doesn’t leave the palace until later. So where is Tom? Well at this point we don’t know Bess is in Astlan, so we should assume one of the blue ones is Tom.
Obviously if Tom is a blue, he is the lone one. That would make him an Archdemon. However, if the light blue one is the lone one, then it may be the mirror isn’t exactly calibrated to the arbitrary human classification of demons. That would mean that he is a very very strong 4, something we already knew/suspected. However, if the dark blue was the lone one… that would be interesting. It would mean Tom outranks either Ramses or Exador at this point and is unquestionably an Archdemon.
Final question: is Tom an Archdemon at this point?