A mediator is a "go between" when two parties are at odds with each other. He facilitates communication between the two, so Jesus is the bridge that facilitates our communication with God.....our prayers must be delivered through Jesus.
No sorry, I cannot agree with that. At the transfiguration Peter, James and John saw Jesus in his glory. There was no shield then.
Read it in the Tanakh.....
"6 And the Lord passed before him and proclaimed: Lord, Lord, benevolent God, Who is compassionate and gracious, slow to anger and abundant in loving kindness and truth, ווַיַּֽעֲבֹ֨ר יְהֹוָ֥ה | עַל־פָּנָיו֘ וַיִּקְרָא֒ יְהֹוָ֣ה | יְהֹוָ֔ה אֵ֥ל רַח֖וּם וְחַנּ֑וּן אֶ֥רֶךְ אַפַּ֖יִם וְרַב־חֶ֥סֶד וֶֽאֱמֶֽת:"
It plainly states that it was
"יְהֹוָ֔ה" and the setting here was when Moses received the Ten Commandments.....
Verses 4-6.....
"4 So he [Moses] hewed two stone tablets like the first ones, and Moses arose early in the morning and ascended Mount Sinai as the Lord had commanded him, and he took two stone tablets in his hand.
5 And the Lord descended in the cloud and stood with him there, and He called out in the name of the Lord."
On that occasion God came down in the cloud.....
Exodus 33:18-23 is when Moses asked to see God's glory....
"And he said: "Show me, now, Your glory!"
19 He said: "I will let all My goodness pass before you; I will proclaim the name of the Lord before you, and I will favor when I wish to favor, and I will have compassion when I wish to have compassion."
20 And He said, "You will not be able to see My face, for man shall not see Me and live."
21 And the Lord said: "Behold, there is a place with Me, and you shall stand on the rock. וַיֹּ֣אמֶר יְהֹוָ֔ה הִנֵּ֥ה מָק֖וֹם אִתִּ֑י וְנִצַּבְתָּ֖ עַל־הַצּֽוּר:
22 And it shall be that when My glory passes by, I will place you into the cleft of the rock, and I will cover you with My hand until I have passed by.
23 Then I will remove My hand, and you will see My back but My face shall not be seen."(Tanakh)
The physical protection of Moses was a concern to God....so he provided it.
So who was this? It says "the LORD" and it carries his name in the Hebrew text. We can speculate all we like, but the scripture says it was Yahweh.