Did you ever notice how many times the devil is referenced when the narrator is talking about Petrovich? Go back and check. It's kinda suspicious isn't it? Those references aren't just there for fun; they're trying to tell us something: Petrovich is the devil.
If you were wondering why the only other named character in this story is the insignificant tailor, there's your answer. He's not just a tailor, but also the devil that is attempting to lure Akaky over to the dark side. Just like Darth Vader.
The signs are everywhere, but some of them are old-school and you might not notice them without some help. Back in the day, the devil was always characterized as having one eye, a tough toenail, and was often faceless. Petrovich also has one eye, a tough toenail, and he happens to have a snuffbox where the general has no face.
That's not even to mention that when we first meet him, he is shrouded in smoke. Hell fires, perhaps? Plus he engages in unchristian activities. The narrator says: "[He] began to drink heavily on all holidays, at first on the great ones, and then on all church festivals without discrimination, wherever a cross stood in the calendar" (20). Good Christians don't drink on the Sabbath, and especially not on high holy days. Petrovich, on the other hand, only drinks on those days.
Then of course, there are the times when the narrator almost straight-up tells us that he's Satan. For example: "Petrovich was in a sober condition, and therefore rough, taciturn, and inclined to demand, Satan only knows what price" (25). There is also this moment: "Petrovich's eye was very much askew, in fact, after Saturday: his head drooped, and he was very sleepy; but for all that, as soon as he knew what the question was, it seemed as though Satan jogged his memory" (52). There are many more moments, and we could quote them here but we think that you get the point. We hope that you're convinced, because that's important for the next point.
Petrovich being Satan is only relevant because he tempts Akaky. Before going to Petrovich, Akaky is totally content with his life. He doesn't mind that he's poor, he doesn't mind that people make fun of him, and he doesn't even mind that people throw their trash on him. Not only that, but he loves his job, is really good at it, and isn't mean to anyone. If you think about it that way, Akaky is actually pretty decent and easygoing guy.
But Petrovich disrupts all that. Once he convinces Akaky that he needs a new coat, the lowly official starts to change. He's not content anymore. He's not dedicated to his job, and even starts making mistakes. In the end he's transformed into a vengeful spirit. That's basically the opposite of what he used to be.
Petrovich's path is the path to the dark side. Yoda would have told Akaky, "If once you start down the dark path, forever will it dominate your destiny, consume you it will." Instead of freaking out about his lost coat, he should have learned what Yoda tells his Jedi in training: "Attachment leads to jealousy. The shadow of greed, that is. Train yourself to let go of everything you fear to lose."