Commentaries:
Obviously, this is no man—he just looks like a man. The Bible does not name who it is, but he is undoubtedly an angelic creature. The best guess is that it is the same angel Daniel dealt with before, Gabriel.
John W. Ritenbaugh
Satan (Part 1)
What did his clothing hang on, if the common conception of spirit as just an essence is true—that there is not really anything there? Casper the Friendly Ghost seems to be covered in a white sheet, and he goes flitting around, but he has no real form or shape there because that is the common conception of spirit—that there is really nothing there. But with angels, there is something there! Spirit beings have substance, though they are spirit. Notice, he even has a waist (or loins, KJV) as human beings do.
John W. Ritenbaugh
Image and Likeness of God (Part Three)
Other Forerunner Commentary entries containing Daniel 10:5:
Luke 2:25
Luke 2:30-32
Luke 2:36-38
Revelation 12:7-9