on so-called "Majestic Plural", the only problem with the term is that the
idiom is commonplace and not limited to 'kings' and 'royalty' like the
English word 'majesty'. You might think of it as the 'authoritative
plural', or 'respectful plural'.
Get a concordance of the Hebrew Bible and look at
be`alim, used for a singular 'owner'.
adonim, used for a singular 'master'
elohim, used for singular 'God'.
You will find these at all strata, from legal (Ex 21) and narrative (Gn 24)
literature in Tora and onwards.