Thanks for the word hendiadys; I know (intimately) of the practice, but never had a word for it. My own certificate of appointment to my current (lawyer) job says that I am "authorized and empowered" to "execute and fulfill" my duties and "to have and to hold" my office, with all of its "powers, privileges, and emoluments."Legalese (lawyer's language) often includes what I remember as hendiadys from school days: you use a pair of words with the same meaning, nouns or adjectives, connected with "and", to make the meaning stronger. In their case, I think they use it to minimize the possibility that different nuances in the meanings are not covered.
I think it is typical in contracts, e.g., license agreements for software: "In any and every possible case you are bound to this EULA and you owe your soul to Microsoft".
Not exactly. The meaning is that it should be used in acccordance with the law or else for legal/legitimate/lawful purposes.I wonder if the meaning of the Greek phrase is something like" this certificate is a legally valid document"?