"The blasts of compressed air from this close-range weapon strip armor and components from machines without the need to aim precisely, leaving them more vulnerable to follow-up attacks."
The Tearblaster is a short-range ranged weapon that fires blasts of compressed air that easily strip armor and components from machines and stagger human enemies.
It is given as a reward upon the completion of the Hunters' Blind side quest. However, as of patch 1.13, it has become available for purchase from certain merchants after completing the quest.
The Tearblaster ammo pouch can hold up to 30 charges at a time if upgraded to maximum, while the weapon itself can hold 10 charges before needing to reload. The damage output of the Tearblaster is the same on all difficulties except Story Mode and Ultra Hard.
The Tearblaster is one of only two weapons of "Very Rare" value to not have Adept version in New Game+, the other is Sylens' Lance. As of Frozen Wilds, it also becomes the only weapon that is both unmodifiable and has no alternate/superior variant.
The weapon that Dervahl uses to fight Aloy during the quest The Sun Shall Fall seems to be a Tearblaster, if not a weapon of similar build. The most notable difference from Aloy's is that Dervahl's sonic weapon CAN inflict damage.