Whether its March[er Lord], Margrave, Marquisat, you have examples across Europe of this form of title which was given to lords on the frontiers [usually of Christendom], whether it be in Southern France (Spanish March), or East Germania etc. How were these divided differently from regular Counties/Comte or Duchies/Dux/Duce? And how did the title of Margrave or Marquis evolve from Marcher Lord, or did they not at all?
Did Marcher Lords have more power (hence more autocratic) as it was an unsettled border region, that needed a more direct hand from a military figure, or was it the complete opposite, where the King created these titles, so he could have a weak governor in charge, so he/she could wield authority in subduing the rough border regions of a Kingdom, as an open battleground, not yet ready for permanent nobility.
Following on from my previous post on this (which included etymology of marquis et al), I'm going to use the English terms count, duke and marquis for purposes of getting to the point. For readers, it's also important to establish that marquis derives from the same word as march, ie the latin for 'frontier' or 'border' (incidentally the same derivation for the English word margin).
The marquis of the Carolingian era and the marquis of the late medieval-early modern era were almost entirely different things, and unfortunately a non-period specific question like this quickly results in eliding all differences across 700 years into a single concept. This is particularly important because a fixed nature of a medieval title like marquis, count, duke, is really the creation of historiography and political need in the late middle ages.
The title 'marquis' was effectively a Carolingian invention, and was considered equal to a 'count', and often was interchangeable with 'count'. For example the 'count of the marches of Brittany' was also a 'marquis'.
The fixed concept of a 'march' develops within Charlemagne's reign, and in particular between 780 and 810; the Carolingians by this point had fought nearly 80 years of expansionist wars and by and large settled the limits of the empire. At this point there develops within Charlemagne's court an acute sense of what is the frontier of the empire to be defended against invasion, and at the same time (perhaps not coincidentally) succession planning for Charlemagne's three sons includes concern for defending the tripartite empire's borders.
Historians are not entirely clear about the exact role of counts of the marches, but a clue is given in a late Carolingian record:
The prudent Charles gave none of his counts at any time more than one county, with the exception of those in the march and on the frontier with the barbarians. ^1
Marquis are interchangeably referred to as praefecti (prefect, Roman territorial governors), particularly on the Breton, Bavarian and Fruili frontiers. To confuse things even further, one marquis is referred to as comes et marcae Foriuliensis praefectus: count, marquis and prefect all at once.
As bests as we can understand, the marquis under Charlemagne has slightly different requirements in the organization and use of an army. In reference to the Spanish march:
the Spanish fugitives [Christians who had fleed Arab Spain], like other freemen, had to do military service with their counts, and provide specific guard- and reconnoitering duties, wactae. ^2
Moreover, apparently military leaders were selected to be counts of marches. What comes together then is an idea that marches were organized far more defensively, with continually standing armies of a unique type, to create what are often called by the Carolingians the 'deserts' of borderlands with foreign kingdoms. Under the Carolingians, although writs for organization of the army were managed by the king (or mayor of the palace), the management of it was local. This was how the Carolingians attempted to manage such a large land mass.
After the Carolingians (say post 900), the title 'marquis' takes the same path as do count and duke: the title shifts from an office representing the king and kingdom to a 'private' title born by various aristocracy, claimed through either land grabs in conflicts or through inheritance (this is usually referred to as post-Carolingian political fragmentation). Thus, the majority of 'marquis' found in the high middle ages in the western European mainland really reflect the same geographic zones of frontiers under Charlemagne: southern France, parts of west France, parts of Germany, and some Italians. By this time however they have entirely lost their original meaning in two ways:
there was no central 'empire' whose 'borders' needed protection (the HRE of the high middle ages does not have the same organization as the Carolingians, being more confederated territories); for example, the marquis of Provence (a title which shifted between whole numbers of families in the high middle ages) was certainly not on a 'frontier' at this point, and owed no allegiance to any monarch, or perhaps maintained allegiance to various parties simultaneously.
titles such as count, duke and marquis do not reflect an office of the kingdom; they are no longer an office at all, and never will be again in Europe;
By the late middle ages, marquis, duke and count (and a host of other titles such as baron, viscount, etc) are entirely aristocratic name plates associated with lands and property. True, in the late middle ages and through the early modern era, monarchs could create new titles, and sometimes those would be marquis, and they might be on frontiers (English marquis might be an example here). But they weren't offices of the defence of borders on behalf of the king: armies by this time were centrally managed and organized. Aristocracy were by this point owners or managers of land and the means of economic production.
^1,2 Walter Pohl, I. Ian N. Wood, Helmut Reimitz. The Transformation of the Frontiers: From Late Antiquity to the Carolingians. (Brill, 2001). Quotes are from the essay 'The Creation of the Carolingian Frontier System' by Herwig Wolfram.