All Prayer

There is a question whether "all prayer" in Ephesians 6:18 is to be considered part of the armor of God or not. True, it is not given a symbol, such as a helmet or breastplate (perhaps Paul could not think of a good analogy with the warfare of his day). But it is so closely connected with this passage that it is otherwise unclear what it is doing here and why Paul is so abruptly changing the subject. Also, there is a connection between prayer and spiritual warfare (1 Peter 5:6-8; Matthew 6:13; Mark 9:29).
And prayer is the Christians most powerful weapon, transcending time and space (Matthew 21:21; Philippians 4:6,7; 1 John 5:14,15). Therefore prayer is a key element in our battle with the devil and his minions. It should also be noted that in this passage (Ephesians 6:18-20) the emphasis is on prayer for others and not primarily ourselves. Paul himself is admitting that he needs it for his ministry. Prayer is a way we can not only fight demonic forces in our own life but support others in their struggles. And we all need that assistance when dealing with Satan and his schemes.