The question is, "what does it actually say?"
1 Samuel 28:12-20 KJV
12) And when
the woman saw Samuel, she cried with a loud voice: and the woman spake to Saul, saying, Why hast thou deceived me? for thou art Saul.
13) And the king said unto her, Be not afraid: for what sawest thou? And the woman said unto Saul, I saw gods ascending out of the earth.
14) And he said unto her, What form is he of? And she said, An old man cometh up; and he is covered with a mantle.
And Saul perceived that it was Samuel, and he stooped with his face to the ground, and bowed himself.
15) And
Samuel said to Saul, Why hast thou disquieted me, to bring me up? And Saul answered, I am sore distressed; for the Philistines make war against me, and God is departed from me, and answereth me no more, neither by prophets, nor by dreams: therefore I have called thee, that thou mayest make known unto me what I shall do.
16)
Then said Samuel, Wherefore then dost thou ask of me, seeing the LORD is departed from thee, and is become thine enemy?
17) And the LORD hath done to him, as he spake by me: for the LORD hath rent the kingdom out of thine hand, and given it to thy neighbour, even to David:
18) Because thou obeyedst not the voice of the LORD, nor executedst his fierce wrath upon Amalek, therefore hath the LORD done this thing unto thee this day.
19) Moreover the LORD will also deliver Israel with thee into the hand of the Philistines: and to morrow shalt thou and thy sons be with me: the LORD also shall deliver the host of Israel into the hand of the Philistines.
20) Then Saul fell straightway all along on the earth, and was sore afraid, because
of the words of Samuel: and there was no strength in him; for he had eaten no bread all the day, nor all the night.
Your assertion is that this might be considered in the form of "phenomenal language", that doesn't give a literal description of what is happening, rather it gives what the appearance is. So this appeared to Saul to be Samuel, so, whether or not it really was, it's written that way.
An example would be that the sun turns to sackcloth, and the moon to blood. Later in the prophecy we read of the sun scorching men in the bowl judgment. We read of the sun and moon to be darkened when Jesus comes in power and glory. So to me these say that the sun won't actually turn to burlap, and the moon won't turn to actual blood, rather that this is how they will appear.
Luke 2:48 KJV
And when they saw him, they were amazed: and his mother said unto him, Son, why hast thou thus dealt with us? behold, thy father and I have sought thee sorrowing.
Here, Mary speaks the same way, "your father and I", even knowing Jesus was not fathered by Joseph. People often just speak that way. But then Jesus answers accurately, "I must be about My Father's business", referring of course to His real Father.
Matthew 1:15-16 KJV
15) And Eliud begat Eleazar; and Eleazar begat Matthan; and Matthan begat Jacob;
16) And Jacob begat Joseph the husband of Mary, of whom was born Jesus, who is called Christ.
Matthew, giving us the information, doesn't write that way, and does not show Joseph to be Jesus' father.
Luke 2:43 KJV
And when they had fulfilled the days, as they returned, the child Jesus tarried behind in Jerusalem; and Joseph and his mother knew not of it.
Luke recorded Mary's statement, "your father and I" but when giving the narrative account again wrote accurately, "Joseph and His mother". He even adds a disclaimer in his geneology of Jesus,
Luke 3:23 YLT
And Jesus himself was beginning to be about thirty years of age, being, as was supposed, son of Joseph,
John the Baptist / Elijah made for an interesting study in this regard, but concerning them I find a great many statements that have no counterpart in the simple narrative concerning Saul and Samuel.
So this is some of my thought process in looking at this passage. I see a pattern of accurate representation of people, and when there is some variation on that, I'm seeing the Scriptures explain and confirm.
Much love!