Concerning his Son (περ του υιου αυτου). Just as Jesus found himself in the O.T. (Luke 24:27; Luke 24:46). The deity of Christ here stated.

According to the flesh (κατα σαρκα). His real humanity alongside of his real deity. For the descent from David see Matthew 1:1; Matthew 1:6; Matthew 1:20; Luke 1:27; John 7:42; Acts 13:23, etc.