They, along with the dragon arrows, are technically not like other Dragon equipment in that they are not made from dragon metal and are therefore not red in colour. Rather, they are made from a dragon's talons.
Dragon darts were often used by pures in The Wilderness as they hit very quickly and dealt moderate damage; a good way to player kill with them was to throw three darts and change to a more powerful weapon such as a Two-handed sword or Dark bow.
A stronger alternative to dragon darts are blisterwood stakes, which are level 70 and free to make, but they require more effort to obtain. Sagaie are even stronger than the stakes, but they have no off-hand equivalent.