grammaticality - Structure of 'Be you never so high...'

In an English High Court case in 1977, the late Lord Denning summed up the gist of the principle of the rule of law when he said:

To every subject in this land, no matter how powerful, I would use Thomas Fuller’s words over 300 years ago: ‘Be you never so high, the law is above you.’

Source: P7, How the Law Works, Gary Slapper

I know that Thomas Fuller lived in the 1600s, but still want to learn about the grammar and structure.

1. 
   

   What form is be in; it looks the English present subjunctive?

   
   


2. 
   

   How to anatomize/parse/unravel Be you never?
   I can guess the meaning here as "Even if you were so high..."