The Angel is described in the words
"And his face as it were the sun" .
This is clearly the Person of Christ
of the vision in Chapter one.
In that vision, He walks

among the golden candlesticks and He looks were
"as the sun shineth in its strength".
Revelation 1:16

At the Transfiguration in Matthew 17:2 His "face
did shine as the sun".

He appeared in the brightness of the midday sun,
to Saul on the Damascus road.

In the Old Testament, He was spoken as "the sun
of righteousness, arising" with healing in his wings.
Malachi 4:2