The expressions more NP and more of NP have various paraphrases depending on context, but their meanings are generally similar.
In your first example, “he was more of a danger than Pele at the time,” the phrase more of a danger means a greater danger.
Consider a different example, one inspired by the aphorism that “March comes in like a lion and goes out like a lamb,” which means that the weather early in that month is typically harsh but by four weeks later becomes much milder. If one year there were a blizzard on the 24th, one might remark, “Today is more lion than lamb,” which refers implicitly to the aphorism and points out the day’s not conforming with the pattern the aphorism expresses.
In During the emergency, the Governor’s wife was more of a leader than he, the meaning is that she acted more like a leader, or showed more leadership than he.
If a television critic said, “The show’s cancellation is more mercy killing than murder,” it would mean that the series was—perhaps had become—so bad that ceasing its production was almost a favor, and certainly was nothing to object to.