Hmm, intresting stuff:) I would propose that the guardian encountered by the narrator is in fact a mahir, or a close relative of a mahir.
"I saw lurking within its depths a shadow of human form."
This pretty succinctly decribes a Mahir if you ask me.
"The white embers of its eyes stared directly at me"
While m2 mahirs had red eyes, the "embers" part fits the description well.
"I heard a voice like dry leaves whisper of horrors that would befall me if I did not flee."
Compare this to the m2 Mahir's flavor text;
"...an obsidion flame howled in a tongue he understood not, it's words violent, clear and distinct..."
My theory is that the mahir(or mahir cousin) was created artificialy, and bound to the door to scare off intruders. Why didn't it attack the narrator and burn him to a mummified crisp? Not a clue:P Perhaps the mahir was compelled to attack only specific targets, perhaps it was tricked because the narrator was a journeyman, perhaps the spell binding it in place had weakened over the centuries.
