Eragon recovers his strength a little, but he's still pretty shaky.
He finds Cadoc and then Snowfire. Brom is slumped over in Snowfire's saddle, with a nasty gash on his arm.
Saphira calls out to Eragon in his mind, asking if he's okay. When he says he is, she swears bloody vengeance on the Urgals. Eragon tells her there's no need: they already went out—with a bang. Then he slaps his knee and gives Saphira a high-five. Or something.
They need to get out of the village, now, and get Brom some medical attention.
Saphira puts Brom on her back while Eragon leads the horses. As they leave the village behind, Eragon notices the tracks of the Ra'zac.
Then it hits him: he used magic to kill those Urgals! Eragon is super-stoked about that, but he has many questions about this newfound ability. For example, why didn't Brom tell him about this?
They continue on. Saphira scouts ahead for a secluded camping spot. Finally, they settle down for the night and Brom listens to Eragon tell him about the magic blast that he unleashed.
Brom thanks Eragon for saving his life, but then says that Eragon shouldn't have used the power. He had no idea what he was doing and could have destroyed himself and everything around him.
Eragon points out that, if Brom would, you know, teach him about this stuff, then he would know what he's doing.
Brom says that the magic is too powerful and complex a force to teach. There are hard and fast rules to magic that must be adhered to. The punishment for violating them is death.
Eragon presses him: for example?
Brom asks him if he said anything to release the blast. When Eragon replies, "Brisingr," Brom explains that magic stems from an ancient language that "describes the true nature of things, not the superficial aspects that everybody sees" (19.50). The better this language is learned, Brom explains, the more powerful a magician one can become.
Saphira realizes that Brom is himself a magician. She passes this on to Eragon.
Brom admits that he knows a bit, but that he's getting old and is not as strong as a full-fledged Rider like Eragon.
Speaking of old age, it's now bedtime for Brom. Before he goes to sleep, though, he warns Eragon that magic takes as much out of a person as any other difficult physical task. That's what makes it so dangerous. Once you commit to using it, you can't cancel it, so magicians have to know their physical limits well.
Despite Brom's warning, Saphira is stoked about how powerful they are becoming.