Stone Cold Badge
From Paragon Wiki
You took out a filthy traitor to the Port Oakes Vendetti Family.
How to Get
As a Flashback mission, you must complete "Hurt the Traitorous Vendetti" in the Soldier (Level 1-15) section.
Gladiator Badge Unlocked
When you earn this badge, you will unlock the Mook Capo Gladiator badge.