Paul could have given Timothy the entire description of the full armour of God he wrote in Ephesians, and I'm certain he wasn't saying, "Timothy, when I wrote that circular letter to the churches, I gave a list of six things - the belt of truth, the breastplate of righteousness, the gospel of peace, the shield of faith, the helmet of salvation and the sword of the Spirit. Really, the only ones you need are the shield of faith and the breastplate of righteousness (which leads to a good conscience)."