You probably picked up a crossbow by accident while reaching the corpse and the inventory was full because of potions from the lost belt, so the HoZ and the weapon wouldn't fit into the inventory and couldn't be picked up while not noticing that. That's tough, but I guess you learned a good lesson: Never equip or pick up anything while retrieving the corpse, except you have plenty of inventory space!
LOL!You most likely picked up a crossbow by mistake when approaching the body, and your inventory was already full due to potions from the missing belt, thus the HoZ and weapon wouldn't fit in the inventory and couldn't be picked up while you were unaware. That was difficult, but I assume you learnt a valuable lesson: never equip or pick up anything when collecting the body unless you have enough of inventory space!