The One referent in this passage is the Father our great God and Savior. Incidentally, the interpretation of Titus 2:13 described in this video is insisted upon by Gordon Fee, a Trinitarian theologian, and Professor Emeritus of New Testament Studies at Regent College.

The Trinity Delusion
http://www.angelfire.com/space/thegospeltruth/trinity/verses/Titus2_13.html
THE
Blessed HOPE
AND
APPEARANCE of our great God and Savior's glory
= Jesus

THE
Blessed HOPE
AND
APPEARANCE of [the Father's] glory
= Jesus

The Son of Man will come in the glory of his Father. Matthew 16:27.

The Trinity Delusion website
http://www.angelfire.com/space/thegospeltruth/trinity.html