RuneScape Classic Wiki
RuneScape Classic Wiki
The main RuneScape Wiki has an article on: Iron Throwing Dart
The Old School RuneScape Wiki also has an article on Iron Throwing Dart.

An Iron Throwing Dart is a throwing dart which can be obtained by smashing Strange Barrels or by attaching feathers to iron dart tips with level 22 fletching. Granting 1 fletching exp per dart created. It can be equipped at any level.

Weapon poison can be used on them to create Poisoned Iron Throwing Darts.

Like all throwing darts, they provide no WeaponAim or WeaponPower, and when they are equipped, they are invisible to other players.