"The Seven Deadly Sins" - Reasoning: Each sentence structure portrays one of the seven deadly sins from Christian theology, with the exception of the final 5 words. In order according to the riddle, these are; gluttony, sloth, wrath, lust, greed, pride and envy. The final 5 words, "whose feet on Earth remain", act in conjunction with the section on envy, demonstrating the perspective of a sinner in hell, who is envious of those still alive, and thus can still repent for their sins in order to enter Heaven.
"Wind" - Reasoning: "Eye" sounds like "i", and the fact that the answer "cannot see" hints that this is the case. Wind, especially high wind, can feel biting, and in literature, the wind is often said to bring a "biting cold", or similar. The voice of the wind is depicted as being quiet or loud, depending on how strong the wind is. Loud winds are often associated with keeping people up during the night.
"Leaves" - Reasoning: Leaves contain veins to transport water through the leaf, and as people would need to be up close to see them. Hence, these veins go unseen as they spend most of their time up in trees attached to branches. You only really get to see them when they fall to the ground.
"Midnight" - Reasoning: The riddle is all about following something through to the end - a day. Once the day reaches its end, at midnight, when all the hours of the day are gone, right down to the last second, the clock resets. Thus, it marks both the end of a day and the beginning of a new one.