What chapter does eragon get his blue sword?

yes named brisingr and when he says its name it catches on fire witch is blue!!! at first noone can explain why but most ppl think it is because that is the true name of the blade.. But eragon faces a problem because the elf that usally makes the sWord swore a oath never to make another riders sWord.. so she does this weird mind link and helps eragon fordge it...