Only Jesus has the necessary authority to call people to be faithful unto death. Commanding people to be faithful unto death announces that it is better to be faithful to Jesus than it is to go on living. Only Jesus can make that announcement. Only Jesus can adequately reward that kind of sacrifice.
The death that results from faithfulness to Christ points to the only life worth living: the life of faithfulness to Jesus.
Audio from this morning here: Revelation 2:8–11, Faithful unto Death