The Four Gifts of Erdas are Heart of the Land (a golden amulet), The Wildcat's Claw (a sword), Stormspeaker (a crown), and The Dragon's Eye (a green jewel). It is said that Takoda and Xanthe were guarding this knowledge. Apparently The Redcloaks know what these are as well.
In The Dragon’s Eye, Meilin finds an ancient piece of paper stating how to make bond tokens (written by Xin Kao Dai). Then, the heroes make bond tokens. Rollan uses Tarik's cloak to make him able to fly, Meilin uses a hairpin passed down by Zhongese leaders to make the person possessing it able to heal and calm, like Jhi. Abeke turns her bow into a bond token, making her agile as Uraza, and Conor uses a shepherd's crook into a wonder which strengthens the senses.