The 144,000 are “sealed” by the “four angels” in Rev. 7: 1-3. They are “sealed” by “angels to whom is given power over the nations of the earth” in D&C 77: 11.
In the account of Revelation, they are sealed before “the earth, …the sea, …the trees” are “hurt” in the last days. (Rev. 7: 3.) This timing necessarily requires the “sealing” to precede great distresses which to us are still future.
-What does it mean to have an “angel to whom is given power” come and “seal the servants of our God in their foreheads?” (D&C 77: 11; Rev. 7: 3.)
-Are men, or institutions, in control of this process?
-How would you expect this to happen?
-Does the “sealing” imply some kind of ordination?
-Is this connected in any way to the “oath and covenant of the priesthood?”
On that last question, D&C 84: 33-42, is often read, explained, and taught. But a context is imposed on the words that presumes a certain meaning. What if that context is incomplete, or merely a tradition, and not what the words were meant to convey? Here are the verses with another possible context inserted into them as they proceed:
For whoso is faithful unto the obtaining these two priesthoods of which I have spoken, and the magnifying their calling [notice “calling” is singular], are sanctified by the Spirit unto the renewing of their bodies [here? now? in the resurrection?]. They become the sons of Moses and of Aaron [who are “sons of Levi” and associated with the Aaronic or first priesthood] and the seed of Abraham [who is the father of the righteous, and one of the “fathers in heaven” to whom we must connect or be “utterly wasted” at the Lord’s return; and is associated with the second priesthood], and the church and kingdom, and the elect of God [this body of chosen individuals are a “church” and that church is confined to the “elect”]. And also all they who receive this priesthood receive me, saith the Lord [in other words, the Lord makes Himself known to them, for that is how He is “received”]; For he that receiveth my servants [who are His “servants?] receiveth me; And he that receiveth me receiveth my Father [is this what Mosiah 5: 15 is referring to when it says Christ will ‘bring you to heaven, that you may have eternal life?’]; And he that receiveth my Father receiveth my Father’s kingdom; therefore all that my Father hath shall be given unto him [in other words, the promise of exaltation and eternal life. Therefore, obtaining these two ordinations is directly connected with the “servants” and then the ministry of the Son, and the introduction to the Father]. And this is according to the oath and covenant which belongeth to the priesthood. Therefore, all those who receive the priesthood, receive this oath and covenant of my Father [in other words, they have knowledge from the Father that they are His, will inherit from Him all He has, and learned this as a result of the Son’s ministry with them], which he cannot break, neither can it be moved. But whoso breaketh this covenant after he hath received it, and altogether turneth therefrom, shall not have forgiveness of sins in this world nor in the world to come [because they have knowledge obtained from the Son, and a covenant obtained from the Father, and if they turn away they must rebel against the Godhead, whom they have come to know. They become ‘sons of Perdition’ because this is willful and known rebellion]. And wo unto all those who come not unto this priesthood [because if you do not receive this, you do not receive the fullness of the Gospel, and you do not have knowledge that will save you] which ye have received, which I now confirm upon you who are present this day, by mine own voice out of the heavens [because the higher priesthood is only given by the “voice of God” as described in JST Gen. 14: 29: “And it was delivered unto men by the calling of his own voice” -see also JST Gen. 14: 26-29. This is why the “ordination” is confirmed by God’s voice here]; and even I have given the heavenly hosts and mine angels charge concerning you [which is how the “sealing” of the 144,000 will be connected to the “angels” who have “authority” in the verses which describe these events].
I have inserted a possible new context into the words for you to consider. I would remind you, however, that scripture is not something for “private interpretation,” but can only be unlocked through the Holy Ghost. (2 Peter 1: 20; see also JS-H 1: 74.) The meaning belongs to and is controlled by God.