The Conquering Hero

Usually translated "He who overcomes", it is probably better translated, "he who conquers" or "the victorious one". 

The Greek term "ho vikom" is a military term, indicating winning a battle.  Jesus is using it to refer to those who listen to the exhortation in the letter.  In the case of the Ephesians, to repent of their lack of love and to endure in the faithfulness they have already stood in.  For the other churches, it might be one who endures through persecution, or the one who resists idolatry.