The feudal system of Arvum has persisted relatively unchanged for well over a thousand years, with the only significant changes happening during the Reckoning era which saw the five separate independent kingdoms/regions of Arvum become unified under the crown and forge the Compact. The feudal society works with a combination of sworn swords on one's individual demesne and then in turn granting land by means of enfeoffment, in the archaic terms of ancient Arvum that are seldom used today.
Technically speaking, all land in Arvum could be considered to belonging to the Crown, but is then invested in the keeping of vassals. The feudal system of Arvum uses a hierarchial structure of the land being divided up and invested in others, where a lord's own holding is referred to as their demesne (or domain), and the individuals living on the land that serve them personally and have vows of service to them are their sworn servants, and soldiers are often referred to as sworn swords. New demesnes are created by granting land to another family (or individual founding a family) that will hold land independently for their lord as a bannerman, creating this independent fief for them through enfeoffment. This is often referred to as 'a bannerman grant' or 'founding a bannerman house' or 'granting a fief' or the like.
A lord traditionally has complete autonomy in their domain, ruling their demesne with little traditional oversight and passing all their own laws and customs in their own demesnes. There is no codified universal system of law in Arvum, but in practice most of the laws of one domain to the next are very similar, as the Faith can bring immense pressure to bear on any individual lord, and more than one petty lord passing flagrantly unjust laws has been crushed either by the templars of the Faith or by their bannerlord (the lord's direct liege that granted their family its fief). In return for the autonomy, a bannerman is expected to maintain the peace in their own domain, collect and pay taxes to their bannerlord no less than five percent of their gross income from the domain, provide use of their domain's army to their bannerlord in time of war (whenever their lord calls their banners), keep the peace and maintain just laws. Houses that break that agreement could find themselves made outlaw and effectively become among the Abandoned, banished from the Compact.
Due to the autonomy, traditionally the bannerlords execute very little control over their bannermen- a baron taking any action to the welfare of his own barony is not expected to have to inform his count, nor is the marquis holds the banners for two counts below him and their baronies below them expected to keep his bannermen informed of every decision he passes or seek their counsel. There is, of course, politeness and most lords would want to have some reasonable warning if their bannerlord will be taking some action that will impact them and vice versa, but houses in the same feudal hierarchy will act more like friendly allied powers than they would in any kind of employer and employee relationship. Afterall, for absolute direct control, that's what sworn swords in their own demesnes are for.
For common terms: most sworn servants will refer to the direct person that holds thier vows as their liege lord or liege lady or the like. For the lord of their lord, often called the bannerlord for whom their direct lord is sworn to, there is no direct tie of loyalty. In other words, knights sworn to a baroness do not have any direct loyalty to the countess whom the baroness is sworn to in turn, or to the marquessa who the countess is sworn to, or the duchess the marquessa is sworn to, or the princess the duchess is sworn to, or the queen the princess is sworn to. Their loyalty and their oaths of fealty are all held directly, they have in practical terms no direct ties above that, and that is entirely the responsibility of the bannerman. Since 'my lord' or 'my liege' can be ambiguous in some cases, generally those terms mean the direct holder of their vow of loyalty. A knight for a baroness would use 'my liege-lady' for the baroness, 'my banner-lady' for the countess that holds their liege's fealty, 'my banner-marquis' for the march holder above them, 'my banner-duke' and so on up to the crown. Strictly speaking, civil wars tend to fall very heavily around what the individual lords decide, since loyalty is so closely tied to individual vows of loyalty, and a knight siding with their bannerlord against their direct liege would be seen as an oathbreaker and dishonorable, making it extremely uncommon.