We are led to understand that due to his extremely unimportant qualities, that the House, rank, and even name of this individual were not worthy of discussion, nor indeed, even worthy of recording for posterity in the history the author was laying out for his readers.
It is, of course, the duty of the responsible historian not to waste any reader's time with any trivial or inconsequential information. Such information becomes a burden on the mind of the reader, needlessly distracting him from the fullest comprehension of the more important events being described. This can lead to lack of clarity on the part of the narrative, and impede the reader in their appreciation for the events as they unfolded.
At the same time, an individual, however unimportant, who touches on events key to the history being relayed must necessarily be mentioned at least in passing. Omitting the role of such a person completely would run the risk of allowing the reader to become confused as to exactly how certain events had taken place, and in what precise order.
For example, in the case of The Messenger, had his role not been disclosed in the narrative of the history that the author had so ably provided, then it would remain unexplained to the reader just how exactly Khaavren, the Captain of the Phoenix Guard at the time of the history being told, became aware of the injuries suffered to a certain Easterner named Vlad Taltos that formed such an important and interesting turn of events within that narrative; indeed, one could well argue (and quite correctly) that these events were, in fact, the primary reason for the history even to be worthy of notice; thereby drawing the attention of the humble historian to record the events and relay them to his readers in a manner appropriate not only to their level of understanding, but also to incite in them a certain intrigue and interest which, while not strictly necessary to the role of the historian, is certainly a valuable and useful ability in relieving the ennui of the reader inasmuch as it is possible to do so without varying from the strict progression of events, one upon another, in the truest and most historically accurate manner achievable.
It is therefore, of course, critical that the course of the narrative never strays too far from the important historical details being relayed with unimportant digression or tangential discussions of an unrelated nature. Such is the duty of the assiduous historian.
We find it gratifying, therefore, that the author chose to spend so little time and energy in the discussion of such an insignificant personage as The Messenger, as this should illustrate just how fully mindful the author was to his solemn responsibilities as an author, and a Historian. The brevity and concise nature of the descriptions of this individual, in relation to his minor role in the history being relayed, is therefore a testament, not only to the author's ability, but also to his keen sense of duty.