This class is far from weaker. Duskblade doesn't in fact get heavy armor casting. This class gains a save bonus and AC bonus from Cha, which is it's primary score, let alone the static raise to AC. Also the Duskblade spell list is quite pathetic. This is all in addition to the fact that this class is more of a casting class and yet gets a better HD.
Lastly this class gains a better form of channeling than the duskblade has, a full 5 levels before it. Let alone the latter increase to it's channel ability. By no means is the duskblade stronger. Also please see my other comment towards the top.