I'm looking for scholarship on the phenomenon of the Bible treating official titles as though they were proper names. Examples of this seem to include: Pharaoh, Abimelekh, Rabshakeh (maybe Agag?), all of which seem to be royal titles, but are used without the "the" as though they are given names.
Related question: Are the words Tartan and Rabshakeh Assyrian titles or proper names in Isaiah?