Why is Brisingr named The seven promises of Eragon Shadeslayer and Saphira Bjartskular?

His promise to heal Elva His promise to go and visit Brom's tomb His promise to avenge Hrothgar His promise to return to Ellesmera to finish his training His promise to avenge Garrow by killing the Ra'zac His promise to wed Roran and Katrina (maybe) Saphira's promise to heal Isidar Mithrim His fealty to Nasuada (maybe)