Friendly reminder, maybe next time watch MORE THAN ONE of the streams, because the previous three streams were JUST community managers and the developer on the latest stream was a SPECIAL GUEST.
Honestly, if you want to fully experience all the new content in 1.3, you'll have to make a new world, because old worlds cannot be made into expert mode and expert mode is required for you to get useful items like the demon heart which lets you have seven accessories and seven vanity accessories, and the worm scarf which reduces all damage taken by 17% (probably the most useful accessory in the game, excluding wings)