Simplify the following text for a Grade 6 native English-speaking person.
Original: Eragon loses but Murtagh leaves him because he has `` tried '' , telling him that Galbatorix will make sure Murtagh 's oaths are stronger next time . He takes Za ` roc from Eragon , because it was Morzan 's sword .
Simplified: Before leaving , Murtagh reveals that Eragon is his brother , and takes Eragon 's sword as well .