The Armor of God - Praying In The Spirit

For a long time I had the impression that the entire armor of God comprises only six pieces (number of man); however in recent times I have come to the realization that there is another piece that God the Father intentionally place in our hands but some had forgotten about it. And that piece of armor is none other than the gift of praying in tongues (or praying in the Spirit).
Ephesians 6:18
New King James Version (NKJV)

¹⁸ praying always with all prayer and supplication in the Spirit, being watchful to this end with all perseverance and supplication for all the saints—

The apostle Paul wrote in Romans 8 that God the Father gave us the Spirit of sonship

Romans 8:12-17

New King James Version (NKJV)

¹² Therefore, brethren, we are debtors—not to the flesh, to live according to the flesh.

¹³ For if you live according to the flesh you will die; but if by the Spirit you put to death the deeds of the body, you will live.

¹⁴For as many as are led by the Spirit of God, these are sons of God.

¹⁵ For you did not receive the spirit of bondage again to fear, but you received the Spirit of adoption by whom we cry out, “Abba, Father.”

¹⁶ The Spirit Himself bears witness with our spirit that we are children of God,

¹⁷ and if children, then heirs—heirs of God and joint heirs with Christ, if indeed we suffer with Him, that we may also be glorified together.

and along with that he also gave us a Helper to make intercession for us when we don't know what we should be praying for.
Romans 8:26-27
New King James Version (NKJV)

²⁶ Likewise the Spirit also helps in our weaknesses. For we do not know what we should pray for as we ought, but the Spirit Himself makes intercession for us^[a] with groanings which cannot be uttered. ²⁷ Now He who searches the hearts knows what the mind of the Spirit is, because He makes intercession for the saints according to the will of God.

It is therefore important that we realize that praying in the Spirit is also relevant and needful in our spiritual walk in the Lord and that as we journey through life, the devil is not going to leave us alone just because we are children of God. He will definitely try his utmost best to attack us but if we know that we know that we are righteous in Christ, he will find the going tough and he will back off but for  a while and look for opportunities to attack again. That is why praying in the Spirit is the ultimate weapon because we would be praying for many things (even for our future) without full comprehension of what we have prayed for and then when the situation turns out for our good, we give the Lord our loudest praise and worship.
And so, for the believer, there is actually seven pieces of armor that we have in our fight against the devil and we need to be constantly using all the seven pieces for our full benefit. Seven in the scriptures is the number for completeness and perfection.