Summarizing the contents of Heb 7:26, Heb 7:27. - The law constitutes weak men high priests. God's sworn declaration constitutes a son, perfected forevermore. Ἀνθρώπους men, many in number as contrasted with one Son. Ἔχοντας ἀσθένειαν having infirmity, stronger than ἀσθενεῖς weak, which might imply only special exhibitions of weakness, while having infirmity indicates a general characteristic. See on Joh 16:22.
A son
Again the high-priesthood is bound up with sonship, as in Heb 5:5, Heb 5:6.