Another cherished and seemingly important weapon was (re)introduced on Monday's episode of Game of Thrones during Littlefinger's short exchange with Bran. As the two sit down to talk, Littlefinger gifts Bran with a dagger that holds a great amount of significance to him. But Lord Baelish isn't the only person to whom the gift is important; the somewhat questionable gift is actually used during an attempt to murder Bran back in season one.
To jog your memory a little, Joffrey basically puts a hit out on Bran after discovering that he survives the fall from the window that Jaime pushes him out of. But when one of his men arrives in Winterfell to kill Bran while he's in a coma, Catelyn intercepts him, and the assassin is later taken out by Bran's direwolf, Summer.
The dagger that we see Littlefinger give to Bran this week is the same weapon that the hitman wields during his attempt to kill the mother and son. Of course, receiving a weapon that has previously been used during an attempt on your own life as a gift doesn't exactly seem ideal, but Littlefinger justifies it by telling Bran that the dagger is sort of a catalyst for all of the events that have transpired on the show to date — and he isn't exactly wrong. Had it not been the two attempts on Bran's life, Game of Thrones would probably be a completely different show right about now.
Another thing that should be noted in terms of the dagger is that it's made of Valyrian steel, which is one of two materials we know of that is able to kill White Walkers. Jon Snow and the Northerners are gearing up for a fight with the White Walkers that's set to occur any day now. So when that day comes, it's likely that the dagger will prove itself useful. But, for now, we'll just have to wait and see what happens.