I thought the power levels of demons are suppose to be a spectrum? I believe that there isn’t any accurate way to measure a demon’s true strength. There’s the mirror but that only provides the general area.
I don’t think Tom’s a 8th order, look back at the beginning chapters when Lenamare’s school was being besiged and when Jenn was kidnapped.
Tom handled several 3rd order Demons easily, i think there’s a HUGE difference between levels, which become less as demons get stronger.(i don’t count the Demon Princes into it because i think they are exceptions, they outstrip archedemons by a lot)
Tom could (with some difficulty) decimate 2 third order demons and if you look back at Bess,Exador and that other guy, remember that they said about fourth order demons during the match between Tom and Talarius?
They said that a normal fourth order wouldn’t have lasted long and that only really strong 4th orders could withstand the Rod(which Tom was perceived to be) Ramses spoke about the battle as if he considered it difficult but certainly doable, he even states that fifth order demons could definitely overcome the odds and win.