I know there is no such guild as "Spiders", but anyway. If there was
one such guild, the following things might have happened.
The demon code theoretically was cleaned up, fixing a bug in wis in
some demons (thus, some demons would have noticed a change in wis, if
they indeed did exist).
Inquiring the name of the demon, if they would exist, would now fail
for out-of-party people.
Servants would have gotten new command, "dismiss", and the
hypotethical snoop would not work on any channels anymore.
And finally, about the demons. Controlling / channeling too big demons
could provide much more costly + hazardous. This is especially true for
those having low amount of levels in the imaginary spider guild. Also,
the more spider levels you're lacking (scaled somewhat by player level)
would affect the power of the demon.