5 Righteousness shall be the belt of his waist,I found it quite interesting that righteousness and faithfulness were the elements attached to the belt as they easily attach to the Truth as well. In such a way that we are made righteous by the Truth, and Jesus, and our faith in the Truth. Some translations use swash of his loins instead but either way it is something that completes an outfit, connecting it all together and I think that is another bit of the imagery as the Truth really does complete our armour and is the connecting feature of all the other parts of the armour; salvation, righteousness, faith, the readiness of the gospel of faith and the sword of the Spirit. It's the Truth of the gospel that connects and lies under currennt through all the different aspects of the armour of God.
and (A)faithfulness the belt of his loins.
Bringing it back to Christ, Jesus tells that He is the way, the Truth and the life. He is the one that connects it all and is the one through whom we find Truth, whether it be Biblical truth or experiential truth, He is that Truth.