Unskinned shapes in skinned equipment are rendered in the wrong place
In skinned clothes or armour the original engine doesn't show anything that isn't skinned to the actor skeleton. OpenMW sometimes shows the shapes but they ignore the parenting to bones, they're in the wrong place. Hiding the shapes like vanilla may be an unnecessary limitation to future mods, but if rendering them is kept they should appear consistently and be parented to the bones.
To reproduce A_Bonemold_Cuirass_C.nif in Meshes\a
player->additem "bonemold_cuirass" 1
Look at your feet. In openMW it disappears when removing the armour and equipping it again (or when it gets damaged?)