τὸ τέλειον at verse 10, refer to πρόσωπον (face, presence) at verse 12.

πρόσωπον neuter singular. πρόσωπον is translated as: 1. face (Matt 17:2, Mark 1:2, 1 Peter 3:2, etc), 2. presence (Acts 3:19, Acts 5:41, 2 Th 1:9, etc).

The complete face (presence) of Jesus Christ.

2 Corinthians 4:6 

For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in THE FACE OF JESUS CHRIST.

Face to face. We will look at the complete face (presence) of Jesus Christ, and will have the complete knowledge of the glory of God. No more "I know in part".