I think Shin Woo's just human, a human who happens to be Raizel's first real friend. A good person whose strength and integrity make him a shining example of everything that's good about humanity.
I also think that when Raizel dies he will eventually ask Shin Woo to inherit his power(possibly via a soul weapon or something) and take his place as Noblesse for the sake of protecting everyone, which will probably mark the first personal favor Raizel has ever asked of anyone. This will make him a bridge between the nobles of Lukedonia and the modern human world.
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If things end up going this way I also expect he will discover his true secret superpower, that he is inexplicably popular with super-powered girls with introverted personalities. Which will bring about the single greatest love triangle in the history of fiction.....
:wubSeira / Shin Woo / Raskreia:wub
........It's gonna be so great.
http://www.laymark.com/l/o/06.gif