Most Cast Weapons are useless as treasure. In general, monsters can be thought of as using particularly crude and low-quality Weapons that an Adventurer would break with constant use.

There are occasions when you can find Cast Weapons that can be taken as treasure. You should take the tag and leave the physical representation with the Cast and then provide your own physrep for the Weapon if you wish to use it.

If you Disarm a Weapon or Shield from Cast during a battle, you can pick up that Weapon or Shield and use it for the duration of that battle even if there is no Weapon tag attached (assuming that you have the Skill in that particular Weapon to use it.) Once the battle is completed, you must return the physrep to Cast.

Be fair about this = don’t go taking all of the Cast Weapons in order to prevent the Cast from coming back into the battle as other monsters. If you are not using the Weapon, you must give it back to any Cast who is OOG and needs a Weapon to come back into game as another monster.