Actually, if you don't mind, I'm going to stick with the Githyanki example because it hits pretty much exactly the point I'm trying to make.
Remember, the basic point is we're comparing "literary" (for a given value of literary) to conversation . Which, that allows for a more objective comparison because we know, or at least have a pretty good idea, of what is considered conversational English and what isn't. While it might not be up to New Yorker standards, your Githyanki example is very much outside the realm of conversational English.
By and large, about 95% (or a bit more actually) of conversational English is made up of about 5000 words. ((It's actually closer to about 98%)) To give a good comparison, the New York Times generally hits about 93% of the first 2000 words and about 99% of the first 5000. So, if your sentence contains words outside of those first 5000, you are already outside the realm of conversation.
Now, here's the quote again:
That's, by my count, 72 words. Of those 72 words, 6 do not appear in the first 5000 word list (COCA Corpus), "humanoid, gaunt, leathery (although leather does, so, you might count that one), sunken, rictus, wield). So, 10% of your words would almost never appear in any normal conversation. That places you at a higher complexity than the New York times. Also, your choice of words - wield, gaunt, scans for signs - are all geared towards evoking specific responses from the audience. This isn't conversation English. We use words like "wield" in fantasy novels. It's telling that you say "scans for signs" not "looks".
This is a perfect example of how RPGing is not conversational and stripping the higher language out of the descriptions would result in a flat, boring experience. "The human shaped person, taller than average, is thin. It has rough, yellow skin and bags under its eyes and a scary smile. It's armor is of a style you've never seen before. I has a great silver sword that is shiny in the low light. It looks around for enemies. It does not look like it has noticed you but, it might soon. What do you do?"
That's a lot less evocative than your first paragraph, but, is far closer to conversational English.