Needlers are high-power pneumatic guns, firing small darts that do little damage, but which are silent and can deliver a drug or poison. Darts of frozen liquid or even gas are available that disintegrate in the wound, making the weapon almost untracible.
Obviously these are not military weapons, but rather the tools of assassins, police snipers, hunters of live animals and others with special needs.
A character who regularily uses a needler and picks his own Poisons for the weapon may use his Guns skill in place of Medicine for this.