You seem quite reasonable in these aspects; I honestly do respect your ideas (please keep that in mind

)
I am not saying these to irritate you, just a personal theory:
Demons, Satan included, cannot grant powers of their own free-will. Angels and demons do not have free will, that was the gift to humans by God...
so, if a demon does give powers (through any tome), it is because God is allowing that demon to do so. It could be better explained like this: God
knows people are free to do whatever, and He cannot force us to do anything... He'll allow us to fall, in anything, to teach us a lesson; in that
aspect, God allows the demon to do what we... "ask", to teach us a lesson.
With regards to me, I never asked for these... skills/ powers/ abilities... whatever they may be called. It's just like drawing, or music... to
some, it comes natural. Besides, would Satan give powers to someone to fight demons? That would be self-defeating.
(Unless you read the Spawn comics... killing evil increases Hell's army... but then angels kill good to increase Heaven's army... But, Spawn
rebelled, now fights for Giea) (sorry, I'm a Spawn fan)
Anyway, before I get too far off subject, can you understand what it is I'm saying (or trying to)? Also, if you like, look at it from this
perspective: magic, just like a ouija board or gun, is a tool; it is neither good or evil... just the way someone uses it.