Reiters, stradiots, etc were the bridge between knights and light horse (the english also had reivers which were similar to Reiters) and the forerunner of modern cavalry/dragoons
I would say they had heavy armour, no barding, spear (not lance) brace of pistols, no shield (but maybe a buckler)
They arent fast horse, but they are versatile, flexible cavalry units that can grab territory, harrass flanks and een do damage hand to hand.