There is a MASSIVE mis-treatement of the word "perfect" by WT. The word used in the Biblical sense does not mean what WT implies it means. The Greek word eteleiōsen at Heb 7:19 literally means "I complete, accomplish, make perfect". Thus, "perfect" means "complete". This makes sense. The Law could not make ANYTHING complete. That's why they had to sacrifice over and over and over again. But the one sacrifice of Christ could make things complete.
You may also note Hebrews 5:9. Speaking of the Christ, it says: "And after he had been made perfect, he became responsible for everlasting salvation to all those obeying him," I can almost hear you gasping. WHAT? Christ was NOT PERFECT?????!?!??!?! In the definition of the Greek word for perfect, no. While he was in the flesh, he was NOT complete. This does not mean he sinned, for we are told at Hebrews 4:15 that he was "without sin".
As an interesting aside, the old NWT Reference Bible has a footnote on Hebrews 5:9 on the word "perfect". It reads:
Or, “after he had been inaugurated (installed; empowered; consecrated to office).” Gr., te·lei·o·theisʹ. See Le 21:10 ftn. Compare Le 8:33 ftn.
This is one of the proofs that Christ became King long, long, long before 1914, and in their own Bible.