The breastplate of righteousness does not come from ourselves or the things we do. The breastplate of righteousness comes only through faith in what the Lord Jesus Christ has done for us on the cross. It is the breastplate of faith and love. It is a love that is stronger than death and never fails, see 1 Corinthians ch13. Feet fitted with the readiness that comes from the gospel of peace .
Shoes protect our feet.
They enable us to walk long distances at great speed. The shield of a Roman soldier was very large protecting the whole body. The shield of faith protects us from the flaming arrows of the evil one. We are commanded to take up the shield of faith. This indicates that it is not automatically up.