Isaiah 59:17 provides the OT source for the 'helmet of salvation' imagery Paul uses in the armor of God.

1 Thessalonians 5:8 also uses the helmet of salvation, linking it to hope, showing Paul's consistent armor metaphor.

Hebrews 4:12 explicitly describes God's word as a sharp two-edged sword, paralleling the sword of the Spirit.

Revelation 1:16 depicts Christ's mouth with a sharp two-edged sword, identifying the sword with Christ's word.

Revelation 2:16 has Christ warning he will war with the sword of his mouth, same imagery as the Spirit's sword.

Revelation 19:15 shows Christ striking nations with a sharp sword from his mouth, reinforcing the word as weapon.

Matthew 4:4 demonstrates Jesus using scripture as a weapon against Satan, an example of the word as sword.

Matthew 4:7 shows Jesus using another scripture to defeat temptation, illustrating the word's offensive power.

Matthew 4:10 records Jesus quoting scripture to command Satan away, a direct use of the word in spiritual warfare.

Isaiah 49:2 describes the servant's mouth as a sharp sword, an OT image of God's word as a weapon.