What kind of clause or phrase is used in the first part of the following sentence (Frail and seemingly disoriented at times)? Would you elaborate on its structure.
Frail and seemingly disoriented at times, he is looking vulnerable.
In comments BillJ wrote:
It's an adjective phrase called a 'predicative adjunct'. Predicative because it relates to a predicand ("he") and adjunct because it's a supplementary piece of information, non essential, detached from the rest of the clause by a comma (and by a short pause in speech). It's comparable with the predicative complement in "he was frail and seemingly disorientated at times"; we understand that the property of being frail and seemingly disorientated at times applies to the referent of "he".
Category-wise, it's an adjective phrase, comprising a coordination of two adjective phrases "frail" and "seemingly-disorientated at times" (or a coordinated adjective phrase if you prefer). Its function in the clause is that of adjunct (sometimes called an 'adverbial').