You can copy another model's or make your own. Again, the engine doesn't care about the shape or function of the weapon model. You can put a shield on his right hand, or nothing, he'd still swing it like a sword if his skeleton is swordsman. It only cares for the name "primary weapon" and "scondary weapon". If your model only has a "primary weapon" then if you give him a secondary attack in EDU, he'd be wielding nothing, but would still attack.

Weapon "type" is specified in EDU, although it's mostly for sound effects.