A mercantile agent is someone who buys and sells goods for other people. This part of the law says that the agent can still use their normal powers, even if they're not mentioned in this specific part of the law. It's like saying that even though there are some special rules for agents in this section, they can still do all the other things they're normally allowed to do. This makes sure that agents don't lose any of their usual abilities just because of these new rules.