This may have been asked before, but the Great Houses at least (Stark, Lannister, Baratheon, Arryn, ect) all have large bodies of Guardsmen (who I assume are the equivalent of men-at-arms at least) who seem a separate class from household knights.
Would these be the equivalents of personal retainers for these Houses, and do any ‘lesser’ Houses have them?
Pretty much all noble houses above the lowly position of Ser Eustace Osgrey have guardsmen – in fact, they’re obligated to have them, as part of their feudal contract to supply fighting men to their liege lord.
Take Rohanne Webber, for example. House Webber is a minor house, a vassal to a Lesser (though principal) House, with one modest castle and ~60 tiny villages worth of peasants. And yet Lady Webber can assemble 33 fighting men, including six knights and six squires (plus Longinch), a dozen mounted crossbowmen, and nine men-at-arms, without calling a general levy.