A.T. Robertson Commentary Hebrews 7:11

"Now if there was perfection through the Levitical priesthood (for under it hath the people received the law), what further need [was there] that another priest should arise after the order of Melchizedek, and not be reckoned after the order of Aaron?" — Hebrews 7:11 (ASV)

Perfection (τελειωσις). Abstract substantive of τελειοω. More the act than the quality or state (τελειοτης, 6:1). The condition is of the second class, "if there were perfection, etc." The Levitical priesthood failed to give men "a perfectly adequate relation to God" (Moffatt).

Priesthood (ιεροσυνης). Old word, in N.T. only here, verses 12,24. Cf. ιερετια in verse 5. The adjective Λευειτικη occurs in Philo.

Received the law (νενομοθετητα). Perfect passive indicative of νομοθετεω, old compound to enact law (νομοσ, τιθημ), to furnish with law (as here), only other N.T. example in 8:6.

What further need was there? (τις ετ χρεια; ). No copula expressed, but it would normally be ην αν, not just ην: "What need still would there be?"

Another priest (ετερον ιερεα). Of a different line (ετερον), not just one more (αλλον). Accusative of general reference with the infinitive ανιστασθα (present middle of ανιστημ intransitive).

And not to be reckoned (κα ου λεγεσθα). The negative ου belongs rather to the descriptive clause than just to the infinitive.