Binder is an another example of a focused sorcerer. Kravos is a bug in the matrix because he figured out how to eat other people's talents.
We only see Binder summoning demons/spirits, and its allegedly his best skill and the one he's literally named for, but that doesnt mean its the only thing he can do. Just like Ancient Mai being an enchanter who builds wardhounds doesnt mean its all she's capable of.
We never see Kravos alive; his ghost is the the Nightmare Harry had to deal with.
But we know he's a demon summoner in his lifetime because Michael fought and killed one, and that he does dreamwalking, mind magic and necromancy.
Even that fucker Aristedes in Ghost Story did mind control, kinetomancy and multiple forms of concealment spells in addition to the magical tattoos on his skin.
My point was to highlight the fact that different fallen have very different operational styles. Magog is still an unspeakably ancient fallen angle and presumably has lots of juicy lore. He just doesn't use it for anything because he's got even more issues than his siblings.
They also clearly have different skill levels at actually communicating with mortals without breaking Heaven's rules.
Hence the need for tutoring in the first place.
Like I said, it depends both on the Fallen and the host.
I have previously pointed out the difference between Ursiel/Rasmussen, who was so unremarkable that Nicodemus didnt even remember the name of the human host, and Ursiel/Blood On His Soul, the Big Foot master wizard who walked away from getting crushed in Hades kingdom.
As for teaching? It might might be Fallen/Host compatibility.
Or it might be restrictions on how much a Fallen can give their host directly without meeting some benchmarks ; for example, its explicitly stated that Denarians grow in power by inflicting pain and suffering on others, especially those meant to counter them like, but not restricted to, Knights.
Someone like Lartessa might consider it a better choice to put the options for power from her Fallen into unique Fallen-only options like her 1UP when killed, or her unique mental attack
Then grind for normal magic from a nominally mortal teacher.
Other than him being directly called a sorcerer no.
Point of correction:
Nicodemus called Namshiel a teacher of sorcery in his conversation with Harry.
Not a sorcerer.
Nicodemus is a lot more plugged in than ancient spirits are, and where different names for this kind of thing are used they're either the equivalent from another culture or more specific to the relationship.
I don't think it's reasonable to tie the situation in knots to change the meaning of what a character said. On a more meta level, Butcher introduced these terms to inform the audience of that they meant in the context of the Dresden Files. People speak for the sake of the readers and nobody is going to confuse their own setting details for irrelevant IC linguistics games or whatever.
Such as?
Hell, look at the Latin thats the alleged lingua franca of the White Council.
The same terms are used for sorcerer and wizard.
Again, Nicodemus is good at what he does, but he's not perfect.
And I think its unreasonable to use him as a reference for how magic users are classified in the setting.