It seems a little peculiar on paper, but I think if I met one in real life it would very quickly become just the guy's name. Like
Earl. It's namey, since it's a surname. And might slightly allude to MLK Jr. I'd rather meet a
King than, say, a
Deacon or
Bishop or
Cohen, any day. I don't see why it's any less namey than those.
I sort of secretly like the idea of noble titles as names (though there aren't any that particularly appeal to me). It seems like maybe people would respond to them emotionally without realizing it, like they do to uniforms -- in a way that could (one hopes) uplift both
King and the person addressing him. As long as there isn't someone who resents saying the name, or scorns the style - that would cancel out the positive effect.
- mirfak