It was a gift to the Mithral Hall dwarves by Lady Anariel, Sister of Faerûn. The bow is made of wood enspelled not to break or scratch, and the quiver held 20 silver arrows(which can magically teleported back to it quiver/resupplied it self); when one was used the quiver magically replaced it. The bow was used by Catti-brie. Part of the weapon's enchantment (passed to the arrows when they're fired by it) is that the arrows are imbued with crackling energy in flight that causes them to deal far more damage than would be typical for a normal arrow. The energy is probably electrical in nature, as it scorches targets, can set flammables alight, but does not seem to have any particularly enhanced effect upon cold-based creatures.
Another property of Taulmaril the Heartseeker is that the arrow, when fired from the bow, travels at super high speeds compared to a normal bow, allowing it to blast through enemies even when they have armor.