Because this is a blog, it is possible to discuss outside sources beyond the Eth Cepher as well, as we will do when we seek to ascertain who is Leviy in modernity.  It is certainly a question worth asking, and an inquiry worth the making. 

One of the books that was reviewed but not published within the bindings of the Eth Cepher was a work known as the Testimony of the Twelve Patriarchs. From this book we have within its content the testament of Leviy, the third son of Ya’aqov and Leah.

It is within this testament that we find the following commission from the word of YAHUAH to Leviy, well before the birth of Mosheh and Aharon:

You shall stand near YAHUAH, and shall be His minister; And shall declare His mysteries to men, And shall proclaim concerning Him that shall redeem Yisra’el. 11 And by you and Yahudah shall YAHUAH appear among men, Saving every race of men. 12 And from YAHUAH's portion shall be your life, And He shall be your field and vineyard, and fruits, gold, and silver.

This testimony appears to give witness that Leviy was chosen early in his life to declare the mysteries of YAH to men, and to proclaim the redeemer and Savior of Yisra’el.  And when it comes to the declaring of the mysteries to men, consider the words of Devariym 29:29.

Devariym (Deuteronomy) 29:29

Now the secrets of YAHUAH ELOHAYNU, and the revealing to us and our sons forever, is by observance of את eth-all the words of this Torah.

The mysteries are revealed to and for all generations by the observance of all of the words of the Torah, the practice of which is brought by the Leviyim.  The commission within the testimony continues, in applicable part:

Therefore the Most High has heard your prayer, To separate you from iniquity, and that you should become to Him a son, And a servant, and a minister of His presence. 3 The light of knowledge shall you light up in Ya’akov, And as the sun shall you be to all the seed of Yisra’el. 4 And there shall be given to you a blessing, and to all your seed, Until YAHUAH shall visit all the other people in His tender mercies forever. 5 And therefore there have been given to you counsel and understanding, That you might instruct your sons concerning this; 6 Because they that bless Him shall be blessed, And they that curse Him shall perish.

The testimony continues and gives a reference that appears to proclaim that the priesthood of the Leviyim will continue until the coming of Mashiach.

And thereupon the angel opened to me the gates of heaven, and I saw the holy temple, and upon a throne of glory the Most High. And He said to me: Levi, I have given you the blessings of the priesthood until I come and sojourn in the midst of Yisra’el.

It is again within this testimony that Leviy sees the appointment following the seventy shevua of the captivity in Babel.

And there again I saw a vision as the former, after we had spent there seventy days. 2 And I saw seven men in white raiment saying unto me: Arise, put on the robe of the priesthood, and the crown of righteousness, and the breastplate of understanding, and the garment of truth, and the plate of faith, and the turban of the head, and the ephod of prophecy. 3 And they severally carried (these things) and put (them,) on me, and said unto me: 4 From henceforth become a priest of YAHUAH, you and your seed forever. 5 And the first anointed me with holy oil, and gave to me the staff of judgment. 6 The second washed me with pure water, and fed me with bread and wine (even) the most holy things, and clad  me with a holy and glorious robe. 7 The third clothed me with a linen vestment like an ephod. 8 The fourth put round me a girdle like unto purple. 9 The fifth gave me a branch of rich olive. 10 The sixth placed a crown on my head. 11 The seventh placed on my head a diadem of priesthood, and filled my hands with incense, that I might serve as priest to YAHUAH ELOHIYM.  

First, we start with the seven men in white raiment. 

Zakaryahu (Zechariah) 3:9

For behold the stone that I have laid before Yahusha; upon one stone shall be seven eyes: behold, I will engrave the graving thereof, says YAHUAH TSEVA’OT, and I will remove the iniquity of that land in one day.

Chizayon (Revelation) 1:20

The mystery of the seven stars which you saw in my right hand, and the seven golden menorahs. The seven stars are the angels of the seven called out assemblies: and the seven menorahs which you saw are the seven called out assemblies.

Now, let us consider the armour in which Leviy is clothed.  Here the passage provides as follows: Arise, put on the robe of the priesthood (cohen), and the crown (keter) of righteousness (tsedeqah), and the breastplate of understanding (binah), and the garment of truth (emet), and the plate of faith (emunah), and the turban of the head (rosh), and the ephod of prophecy (nevuah).  This is and can be understood as the garment of intercession. 

Chokmah Shalomah (Wisdom of Solomon) 5:16-20

Therefore shall they receive a glorious kingdom, and a beautiful crown from YAHUAH’S hand: for with his right hand shall he cover them, and with his arm shall he protect them. 17 He shall take to him his jealousy for complete armour, and make the creature his weapon for the revenge of his enemies. 18 He shall put on righteousness (tsedeqah) as a breastplate, and true judgment instead of a helmet. 19 He shall take holiness for an invincible shield. 20 His severe wrath shall he sharpen for a sword, and the world shall fight with him against the unwise.

Of course, we see this iterated in Sha’ul.

Cepher Eph’siym (Ephesians) 5:13-17

Wherefore take unto you the whole armour of YAH, that ye may be able to withstand in the evil day, and having done all, to stand. 14 Stand therefore, having your loins girt about with truth (emet), and having on the breastplate of righteousness (tsedeqah); 15 And your feet shod with the preparation of the Besorah of peace (shalom); 16 Above all, taking the shield of faith (emunah), wherewith ye shall be able to quench all the fiery darts of the wicked. 17 And take the helmet of YAHUSHA, and the sword of the RUACH, which is the Word of YAHUAH: