He is one dan / He has one dan

[GeneD]

He's 1 dan/kyu. (It's about Asian ranking system, often seen in martial arts, such as karate and judo).

Personally, I thought that the proper way of saying this was "a first dan". But yesterday I saw a documentary where I heard that as "one dan". Unfortunately, I don't clearly remember if the sentences had the verb "be" or "have", but it seems to me that it was "be" (e.g. "I am one dan"). So my questions are:
1. Is it correct to say "He is one dan"? Could it be that I misheard the sentences (there were a few, but I'm not sure about them all ) and there was the verb "have" instead (e.g. "He has one dan")?
2. Is it possible to say "He is a first dan"?

 

[Tdol]

I would use first dan, and this suggests the same, though I am no martial artist:

https://en.wikipedia.org/wiki/Dan_(rank)

 

[GeneD]

What about a sentence like this: It's a long way from five kyu to one dan?

Here's one of those sentences from the documentary that I can't understand: When you get to one dan/ two dan (it's possible that it should be written "one-dan/ two-dan", I don't know) you start realizing "I don't know anything".

Maybe rephrasing is the key here. Myself, I would use in all the examples I've given ordinal numerals, but I'm merely a learner...

 

[jutfrank]

It's better to say from 5th kyu to 1st dan.