At first I thought this was fan art for that Astartes series on youtube...

But after rewatching all the videos in that series, and being amazed by them again, I realize that this is your own chapter of space-bois

Pretty cool dudes, I got to say.

If I had to invent a name for them, I would go with: Ashen Reapers

...

Ashen Knights?

Blades of Honor?

The Chivalrous Sons?

I don't know