Problem Solver is an origin trait in Destiny 2 that can appear on 22 weapons. An enhanced version exists on crafted and some newer weapons.
What Problem Solver does
Dealing sustained damage to Champion, miniboss, or boss combatants exhausts them and grants this weapon handling and reload speed. Exhausted targets deal reduced outgoing damage.
Enhanced version
Dealing sustained damage to Champion, miniboss, or boss combatants exhausts them and grants this weapon handling and reload speed for a longer duration. Exhausted targets deal reduced outgoing damage.