Determining student understanding of a question based on given answer
You are barking up the wrong tree. 

I can’t speak for all instructors and graders (and it wouldn’t surprise me if your question gets closed for that reason), but, when I’m grading essay questions, I want to know: Can the student answer the question clearly and in a way that demonstrates mastery over the material?

That being what I’m looking for, most of what you listed is smoke and mirrors. 


Sophistication of the language? That means nothing if the answer isn’t accurate. And if your answer is way off, you’ll sound like a pompous ass. 
Length of their answer? Not necessarily. I appreciate depth much more than length. If an answer is long because it shows a deep understanding, that’s fine. If it’s just repeating the same facts over and over again, that can get annoying. 
Use of meta language? Ah, that old trick. Throw enough buzzwords at an answer and hope one of them matches what I’m looking for. (A student tried that on me one time, and I wrote in the margins of the exam: “Your jedi mind tricks do not work on me.”)
Succinctness? That’s probably the only one that you listed that has a shot at impressing me, but it had better be a very good answer if you’re not going to say much.