I take it you're refering to the world models? When you're not wearing the armour.
There are several mods which I've encountered.
Here is what you should know alreay, or have come accross:
World Models: When the item is on the floor, not equiped or in Inventory
Biped Model: When the Item is equipped and you can see it on your Character
You probably need to design a World Model for it. Or just use an existing one like a Steel Dagger or something? I'm no modding expert though; so unfortunately I will not be as much help as people would want

Kind Regards,
Jav'