I tried to have a look around for some discussion on how Player's Handbook II was developed. I found this article where Skip Williams discusses his opinions on the Duskblade, which I will link here:

https://web.archive.org/web/20161031.../cwc/20060905a

I am personally more interested in if there is any material discussing the Knight and the Dragon Shaman

If anyone knows of any articles in a similar vein, or perhaps any related Dragon Magazine articles about Player's Handbook II, I think they could be good to contribute to the discussion as well.