There is an interesting fully metaphoric story about a one named "ذوالقرنین/Zulqarnayn/Two-Eyes Owner" in Quran. [18:83]
I would like to know what does God mean about each metaphor in the story; so is there any comparable historical document(s)?
No historical document. In fact he is not known exactly. Perhaps we already know him but he is not known exactly by identity in Islam. But there are some guess/interpretations based on Hadithes about him.
Some Hadith say he has been a believer with high spiritual rank. But he not been a prophet. A pious and knowledgeable man who God loved him. Like the Luqman لقمان mentioned in Quran.