When it comes to Game of Thrones, the dagger tends to refer to a Valyrian steel dagger that has exchanged hands multiple times over the course of the series. This is not because it is valuable, though it is that, but rather because of its role in one of the central plots that started up in Season 1.
Why Is the Dagger So Important?
When Bran was comatose in bed after being tossed from the tower, a man was sent with a Valyrian steel dagger to kill him. Fortunately, Catelyn managed to fend him off with her bare hands long enough for Summer to enter the room, which resulted in a rather unpleasant but nonetheless well-deserved death for said individual. Unfortunately, there was not a lot of evidence for who had sent the man with the Valyrian steel dagger, though that did not stop the Stark parents from setting out to seek justice.
As it turned out, the Valyrian steel dagger was one of a number that had been owned by Robert. However, while Robert muttered about it being more merciful for Bran to die than for him to live as a handicapped person, he had no real reason to send a man to kill the comatose child of his best friend. As a result, a lot of people suspected Cersei and Jaime, who would have had excellent reason to want Bran dead for the purpose of covering up their incest, which would have seen them executed for high treason if they had been caught in the act. However, that turned out to be a false lead as well because while the two might have had the ruthlessness, Cersei preferred to brazen it out whereas Jaime scorned the idea of sending others to do his killing for him. Instead, the most probable answer is that Joffrey had sent the man with the Valyrian steel dagger in a twisted attempt to please his father, having overheard Robert’s mutterings.
Regardless, the Valyrian steel dagger is important because it became a critical piece in Littlefinger’s plan to start a war between the Starks and the Lannisters. Catelyn trusted him because the two had grown up together in Riverrun. As a result, Ned trusted him when he said that he had lost the dagger to Tyrion when Tyrion had bet on Loras over Jaime at a tournament. This contributed to Cat’s fear that Tyrion’s more numerous guards would overwhelm she and her guard on the road, which is why she called on her father’s vassals to take him prisoner at the inn when her identity was revealed. In turn, this resulted in the first movies of the civil war that has engulfed the continent, which would lead to not just the deaths of multiple Starks but also thousands and thousands of people throughout Westeros.
It remains to be seen what will happen with the Valyrian steel dagger. However, it seems probable that Littlefinger will receive a well-deserved death at some point once the Starks learn the full extent of his involvement of their house’s suffering, which started with him seducing their aunt so that she would convince their parents that the Lannisters were their enemies. Suffice to say that there would be no better way for Littlefinger to receive his comeuppance than the tool that he has wielded to cause so much woe.