This particular cloak is usually of woolen-like material, although it can be leathern. 

It can be handled without harm, and it radiates magic.

A neutralize poison spell will not affect it. 

As soon as the cloak of poisonousness is actually worn, the wearer will be stricken stone dead. 

The cloak can only be removed with a remove curse, which destroys the magical properties of the cloak. If a neutralize poison spell is then used, the person can possibly be revived by a raise dead or resurrection spell, but there is a -10% chance of success because of the poison.

After its effects are known, a small label saying "Nessus Shirt Company" might be seen at your option.