If I have a prop weapon made out of cardboard and/or foam, what are the rules on that? Does it need a Weapon Check? Does it need to look a specific way?
All weapons, even if it made of cardboard and/or foam, needs to be checked at Weapons Check.
Your prop weapon cannot be more than 7 feet (2.13 meters) long or weigh more than 15 pounds (6.8 kilograms).
All swords or bladed martial arts prop weapons must be blunt-edged and cannot have any sort of cutting or sharpened edge (no live steel).