Alric was the heir to the throne of the Province (although he didn't bother claiming it while the Province was a burning ruin overrun by the undead) *and* the leader of the Nine. Since the Nine oversaw the war effort, he was Supreme High Grand Moff of the Light forces. The hierarchy of the Nine was pretty flat, as you'd expect from a small group of extremely powerful and intelligent people, and distance and communication problems made it impossible for Alric to tell everyone what to do directly, so the other members of the Nine generally made their own decisions and commanded their own subsets of the Light armies. But insofar as anyone was in charge in such a chaotic mess, Alric was.
The TFL journals you're talking about say that Alric was "sent by The Head--" not that The Head was his boss. At this time The Nine trusted it implicitly and believed it was an amazing font of information. So when it said Alric needed to go off and find some super-suit of armor, he went. You'll note that the other members of the Nine didn't know why he'd gone--as the leader, Alric had the right to keep his doings a secret from everyone else.
--SiliconDream
