The Cursed Medal is an ominous item that increases the drop rate of Rupees and Treasure. However, it comes with a cost: you cannot access your Adventure Pouch or use a shield.
This means you cannot use potions or defend yourself in a pinch. However, if you can work around the big downside, it’s a great asset for farming, especially if you stack it with other medals.
Even though you can’t physically access your pouch, all pouch items with passive effects will continue to work. This also includes fairies inside bottles.