For a wearable item, such as a helmet or brigandine, you need both the skeletal mesh + model and the static mesh (no skeleton.) Both are just plugged into the item list as per Pirate. The static mesh is used to drop the item in the world. Items that are not wearable (at least under normal circumstances), such as a watermelon or a potato, need only the static mesh. (Or should)
You’ll also need an icon for your item, but videos should also be available for that.