Weeping Shadows of Sorrow
From Halopedia, the Halo wiki
The Weeping Shadows of Sorrow was a Sangheili maximum security penitentiary world where the Seventeenth Arbiter was enclosed before he became such. Prisoners were contained in their cells by Covenant energy shield doors, though mandatory exercise periods allowed them some degree of free-roaming - which was more often than not merely used to engage in battle with each other.
The Warlord, himself was threatened by many of the inmated for the dishonor he had brought upon his clan, but eventually managed to turn them onto the guards and used it as an opportunity to escape, tearing a plasma turret from the defense perimeter to use. He was recaptured and heavily beaten.[1]