how does the reader know that the ancient mariner is a mesmerizer?

AS the wedding guests leave the festivities the Mariner stops a man and we can tell the Mariner has some sort of creepy trance-like qualities. The guest sees this old dude and says, "By thy long grey beard and glittering eye,Now wherefore stopp'st thou me?" The eye gets mentioned allot here. Apperently it has the power to mesmerize the listener,

"He holds him with his glittering eye -

The Wedding-Guest stood still,

And listens like a three years' child:

The Mariner hath his will."

THe poem goes on like this for a very long time. This old Sea-Dog has to have something about him to make a young man sit and listen to his tale rather than try to get some action with the girl he was leaving with.