Dart of Acid

The Dart of Acid +1 is a thrown missile weapon that adds +1 to THAC0 and damage, and also adds 1d6 acid damage if the target fails its Saving Throw vs. Spells.

In-Game Description
"Dart of Acid With the teeth of a black dragon for heads and the mighty wyrm's sinews for shafts, these wicked arrows dissolve into deadly acid on impact."