Plain and intelligible language such as the use of phrases such as "Congress shall make no law" in certain places and phrases like "shall not be infringed" in other places.
Under Marshall's reasoning, the restrictions on Congress in Article I, Section 9, would apply only to Congress, and as such any state would be free to pass bills of attainder or ex post facto laws, suspend the privelige of Writ of Habeas Corpus, or grant titles of nobility. Obviously, if the states intended to apply those restrictions on themselves they could do so by modifying their own laws or constitutions.
Section 10 - Powers prohibited of StatesWhy am I not surprised that you didn't know that?No State shall enter into any Treaty, Alliance, or Confederation; grant Letters of Marque and Reprisal; coin Money; emit Bills of Credit; make any Thing but gold and silver Coin a Tender in Payment of Debts; pass any Bill of Attainder, ex post facto Law, or Law impairing the Obligation of Contracts, or grant any Title of Nobility.