Armsmen are the especially trusted armed, liveried guards in service to the highest-ranked among the High Vor, usually a Count or Countess, occasionally the Count's Heirs. Each Countship is permitted a specific, small number of oathbound, weapon-equipped vassals according to Vorloupulous's Law -- not each individual noble person, but the entire District.
An Armsman is (supposed to be) a non-Vor Tapani citizen of his, her, or their Count's or Countess' District, not only of the Province.
Typical Armsmen are drawn into service after distinguished or noteworthy service to their District as a member of the House Defense Force Fleet or House Defense Guard. A noticeable minority have served in the Tapani Imperium Military, or in the Tapani Ministry of Information, and it is not unusual for two or three Armsmen in a given Province to be distinguished experts in the industry most important to their Great House. Count Vormuntique of Calipsa Province, for example, includes Armsman Tasia Maliade; before she took oath as an Armsman, she spent ten years as the undisputed highest-ranked Mining Standards Inspector overseeing the constantly fluctuating status of the mines on Loni's moons.
When the citizen swears into service as an Armsman, this connection is expected to continue until one or the other dies. There are forms of "soft retirement" where an Armsman can be assigned easy duty, but the Count cannot replace them while the Armsman lives.
If a new Count inherits the title due to the death of their predecessor, all of the prior Count's Armsmen can freely choose whether they want to make a new oath to the incoming Count or not. (And the new Count can choose not to offer the role to his predecessor's Armsmen, but that is a very grave insult.)
An Armsman's word is legally considered to be his Count's word, so it is important that the individuals chosen for Armsmen are trustworthy people whose actions reflect a mindset in line with the Count's priorities and values. Likewise, no one should consider swearing as an Armsman to a High Vor unless one is absolutely certain of that individual's ethics.
Because of this legal definition, an Armsman has an interesting position socially. Within exclusively High Vor spaces, they may be treated as the highest category of "servants". They may be functionally imperceivable, no more a barrier or consideration for the most private of conversations than a piece of furniture. Vor lords who are not in fact snobbish nitwits will nonetheless fail to register the presence of a third person at an argument because that third person was the Armsman of one of the arguing nobles.
The exception would be in the spaces of the family to whom the Armsman is sworn -- a woman would no more forget the existence of her right eye than she would fail to be aware of her family's Armsman.
When exclusively among Low Vor or Tapani non-Vorish citizenry, an Armsman wearing their liege's uniform is very much an extension of the District ruler. Armsmen get bumped to the front of any line or queue. They do not get jostled, ignored, or denied services any more than one would do for the Count in person -- this is not a member of the citizen's caste, this is the Count at one remove.
On the other hand, Armsmen also get stopped by elders who wish to demand a chunk of time outside the posted schedule of their Count's Voice, whether the purpose of that chunk of time is to petition for legal redress ... or to find out when the Count is going to make all these danged young people get a haircut or fix the bridge.
An Armsman has an everyday uniform and a formal or "parade" uniform which will be designed in the two colors of the High Vor House they serve. They also have a weapon, issued to them by their liege (and, legally speaking, owned by that liege), which the Armsman is expected to maintain in excellent working order and to have a high level of skill at using.