Yes, Duke is. I was curious to see if I had been too subtle with that context or not.

Ah, well, I can't really say. I've only read the summary, not the novel itself, unfortunately. Duke didn't get much in the way of attention, nor Elucifer, but the summary did clear up some things that weren't elaborated on much in the game, so I'm assuming that there's probably more detail in the novel itself that was left out for the summary's sake for those two. Here's a link I was directed to if you'd like to see for yourself, though:

http://www.fancomic.com/vesperia/resources/raven/emptymask.htm