All true men-at-arms, whether they were officially knights or not (after Early Middle Ages that was mostly a social title anyway), had a warhorse. Plus aty least one horse they rode outside the battle, the warhorse being only mounted for actual combat (that's where the figure of speech about "mounting your high horse", or getting off it, apparently comes from AFAIK). Then there was also a baggage horse, and men-at-arms of the period the man's gear points to were axpected to furnish a full "lance" (a squire or other lighter trooper plus two archers or crossbowmen plus at least one more guy, all mounted even if only on riding horses).

Men-at-arms were all-purpose troops who could fight equally on foot and on horseback; as the Hundred Years' War progressed, the former became increasingly the norm.

The fellow in the preview, however, apparently isn't a true MAA. He seems to be a representative of the higher end of a type of heavy infantry that did *not* fight in close-order blocks with spears, although such "light" infantry (the term used with considerable reservation here) almost invariably carried spears or polearms as their initial weapons and tended to leave out some or all leg armour in favor of mobility and agility.

I'll admit his sword looks more than a bit weird, though. It doesn't resemble a gladius so much as some early Iron Age designs I've seen in illustrations. Moreover, his body armour's odd; its appereance suggests coat-of-plates, commonly worn over mail before proper plate developed, but AFAIK those normally wrapped around the body. The sort of support strap system he has would look quite at home on the types of Napoleonic cuirassieurs who didn't get bac plates, or a late-medieval or Renaissance pikeman (who often didn't bother with the weight and expense of a back plate).