Some of the 'new features' in the OP have been around since the Ezio trilogy with poison darts that turn enemies against each other
You misread that part:
Part of the new stealth system is the ability to use the environment to your advantage: This includes throwing knives into walls to distract enemies or hiding inside carriages. Or shooting a hallucinogenic dart into a fire to make enemies turn on each other.
Environmental interaction is the new feature, not the items themselves.