I don't think I make this known as often as I should, but Nightcrawler is actually my second favorite X-Men character; with that being said, I absolutely ADORE how he is portrayed here (I'll be jealous of any woman he decides to wed lol). Of course, the choice of clothing here is to die for; I love how the shoulders of his vest jut out to mirror his original costume! There's so much motion in this picture, which befits Kurt's character. And I love that his accoutrements are "asymmetrical" (I put that in quotes for lack of a better term); the chains cris-crossing his torso, his wristbands, and even the hilts of his swords are different from one another.
But the cherry on top is the way you've rendered his face! You had mentioned on your blog that the client had asked for a Cockrum-era Kurt, and the way the shadows play off his face (especially with the texture of the watercolor) really capture that era!