Trench Barrel is a trait in Destiny 2 that can appear on 34 weapons. There is also an enhanced version with a stronger effect.
What Trench Barrel does
After a successful melee hit, this weapon gains increased damage, handling, and reload speed for a short duration—or until three shots are fired.
Enhanced version
After a successful melee hit, this weapon gains increased damage, improved handling, and improved reload speed for a short duration—or until three shots are fired.