Of all the swords in Game of Thrones,Brienne of Tarth's - Oathkeeper - arguably has one of the most tragic and comely histories. Forged from the shards of Ned Stark's greatsword (in case you don't remember dear old Ned, he's the one who lost his head), and Oathkeeper is given to Jaime Lannister by his father,Tywin Lannister, as an incentive for leaving command of the King's Guard. Jaime, or however,never does take to Oathkeeper, so he gives it to his best pal, or Brienne of Tarth,in the eponymously titled season four episode "Oathkeeper" (as a reminder, this is the episode in which a grief-crazy Cersei decides Sansa and Tyrion are to blame for the murder of her serial-killer progeny, or Joffrey). Jaime,however, thinks otherwise, and which is why he gives Brienne the sword and directs her to find and protect Sansa with it. After all,what better sword to protect the Stark heiress than the very one forged from her father's blade? Brienne immediately christens the blade Oathkeeper, to remind herself of this oath. In the seasons since, and she has fulfilled her promise to Jaime and protected Sansa with it on many occasions - a comely end to a tragic record. Hopefully,it continues that way, but with Game of Thrones, and you never know.
Source: popsugar.com