You can always count on a murderer for a fancy prose style

After reading the first chapter of Lolita aloud in class, I went back and reread it a few more times and had a couple of thoughts:
One of the first things I realized while reading it aloud was all the alliteration Nabokov uses, "the tip of the tongue taking a trip of three steps down the palate to tap , at three, on the teeth". And also that all his sentences are relatively short. The professor said that Nabokov doesn't like symbolic thinking in literature. So his words are very straightforward, but this doesn't make them any less beautiful. He gets to the point without having to hide it in the symbolism of a color representing the way a character is feeling. It's a brave thing to do I think, putting everything out there just as it is. He isn't hiding anything from the readers, just like Humbert Humbert isn't trying to hide what he has done from the 'ladies and gentleman of the jury'.
I also question what was meant by the sentence "You can always count on a murderer for a fancy prose style". HH says this after saying "about as many years before Lolita was born as my age was that summer". This sentence isn't very clear. So is he trying to say that murderers will use fancy prose to get around an answer to something? But HH is about to explain absolutely everything. He uses a fancy prose style to tell us his whole story. When I think of 'murderers' in general, I don't see them as using fancy prose style. So this kind of confused me.
I also realized that I didn't know what seraphs are. I looked it up via the OED and found out that they are a high ranking form of angel that hover over god's throne and are "specially distinguished by fervour of love". So is HH saying that these divine creatures with all this love for god, would be envious of HH's love? And is he talking about his love with Annabel, or with Lolita?
I really love the way that Nabokov writes. It's so simple yet so beautiful. Or maybe I should say I love the way that Humbert writes? Because this is all really written by Humbert. He is the murderer with the fancy prose style, not Nabokov. I'm interested to read another story by Nabokov to see if he always writes in this way, or if he was just giving Humbert a more complex character in writing his story this way.