The Lord’s Supper IS even if it’s not special.

“The chief point is the Word and ordinance or command of God. For it has not been invented nor introduced by any man, but without any one’s counsel and deliberation it has been instituted by Christ. Therefore, just as the Ten Commandments, the Lord’s Prayer, and the Creed retain their nature and worth, although you never keep, pray, or believe them, so also does this venerable Sacrament remain undisturbed, so that nothing is detracted or taken from it, even though we employ and dispense it unworthily.”