Shards of Narsil
The Shards of Narsil were the pieces of the famous weapon of Narsil which had been broken by Elendil's fall at the end of the Second Age in the War of the Last Alliance. It was then that Isildur slew Sauron with the hilt of the Shards. Isildur later transported the Shards home with him but he was killed along the way. It was Ohtar, the squire of Isildur who took the Shards and brought them to Rivendell. The pieces were kept as heirlooms until the time came in Third Age 3019 for the shards to be reforged as Andúril.
Portrayal in adaptations
2001: Peter Jackson's The Fellowship of the Ring:
In the film, Narsil is not broken in two, but several parts. Unlike in the book, Aragorn does not bears them with him, but are kept on a display in Rivendell.
Aragorn is seen reverently placing the hilt of Narsil back into the display after Boromir dropped it on the floor.