Hand to hand sound plays on knocked out enemies
Hitting a standing enemy with your fists plays the sound, so far so good.
But when an enemy is knocked out, Morrowind only plays the "damage" sound, for example a "splash" when you hit an unarmored part and see the blood cloud, or an armor sound depending on what part of armor you hit. The hand to hand sound is no longer played.
OpenMW still plays the hand to hand sound on knocked down enemies, on top of the "damage" sound, resulting in two sound effects being played at the same time.