Cavalry

[AqD]

I often asked myself the question if it is realstic that such cavalry like cataphracts are owning every cavalry in melee, even the famous companions of alexander, the hetairoi.

No.

I think the early cataphract armours are so clumsy that they're unsuitable to do anything but frontal charge .... Didn't one Armenian King get dragged down by the lasso of Sarmatian riders? And both of Parthians/Armenians army was destroyed by Alans during their invasion of Armenia (and their cavalry are much lighter!)