Your answer lets me hope to find a solution

but i will try it.
Here whats going wrong in my head:
When TypeID's change the behavior of the item. Then it is possible to change heavy armor to garment TypeID3 '3' -> '1' in Database. This change is needed in media.pk2 too. In this case the server and client should think my armor is garment.
Or is this wrong?
I will try it.
Okay. I tryed it now... I changed TypeID3 to 1 in database and media.pk2. I can wear now armor and garment at the same time. Each armor part is shown as "garment" but the movement speed is equal now.