The one piece of armor that is both offensive and defensive is the sword. When I go into battle, I don't beat my enemy with my shield or try to defeat him with my belt or chase him down with my sandal or throw my helmet at him. I pull my sword out of the sheath and I use it.
Ephesians 6:17 tells us to take up the sword of the Spirit. When we are tempted, the most effective weapon that God has given to us as believers is the sword of the Spirit, which is the Word of God.
Jesus modeled this so beautifully during His temptation in the wilderness. When the devil tried temptation after temptation against Him, Jesus used the sword of the Spirit (see Luke 4:1–13). The devil said, "Why don't you turn a rock into a piece of bread. I know you are hungry."
Jesus said, "It is written, 'Man shall not live by bread alone, but by every word that comes out of the mouth of God.' "
Then the devil said, "Why don't you worship me right now?"
Jesus responded, "It is written, 'You shall worship the Lord God only. Him only you shall serve.' "
"Why don't you cast yourself off of here, and the angels will catch you," Satan said, quoting Scripture out of context.
Jesus responded, bringing the Scripture back into context, "It has been said, 'You shall not tempt the Lord your God.' "
The sword of the Spirit works. So draw your sword, Christian.