Why was Saul so afraid?
David, at the time, was living under the refuge provided by the Philistines. He was
requested / commanded by the king of Gath, to team up with them to fight against
the Israelites. Saul knew David was living in Philistine territory, and this most
likely raised great concern, since Saul knew that God was with David, and he was
beginning to wonder if God was still with him.
Was the risen spirit Samuel or a Demon?
Saul tells the spirit, (Samuel) that he is in great distress due to the Philistine
planned attack on Israel, and that God is no longer with him. He then asks Samuel to
give him advice / direction. Samuel's does not answer Saul's question, rather he
reminds Saul of the past prophecies that he had given him,
1st Samuel 15:25 telling "that his kingdom would be taken
away from him". This most likely is not the message of a demon, since the message does
not stay from the first prophecy given and, with the exception of mentioning David by
name as the new king of Israel, no new information was added.
Regardless of whether Samuel, the prophet was raised in the spirit or in his physical
body, the message given was, Samuel's past prophecy given to Saul. The message given
did not deceive from past prophecy or from what did occur, therefore it could not have
been a demon.
Who actually raised the spirit?
After the medium brought up the spirit of Samuel, she was surprised, and suddenly knew
that the stranger was Saul. Whatever the woman was surprised about, (the raising of
the spirit or the stranger being Saul). The medium was NOT expecting what had
occurred, perhaps she knew the raising was not within her powers and was an act of GOD.
Afterwards she goes to the trouble and expense of killing a fatted calf and making
fresh unleavened bread, (a Jewish custom), for Saul and his
travelers. Whatever is implied whether it be a sense of fear, or humble respect, this
was no regular seance.
Conclusion:
The raising of Samuel, was an act of God. Whether, this was the spirit of Samuel
or his actual physical body, does not really matter, for only past prophecy was
spoken to Saul.