This is a scene during the battle on Fastoon at the last line of defense outside the Court of Azimuth
Garrus had his left arm blown off by a drophyd grenade that detonated prematurely when he picked it up and attempted to throw it back
After this he still attempted to fight, fueled by pain and rage, two other praetorian guards tried to hold him back and take him to the medic but he refused to leave the battle. As a last resort, Rex had to hit him over the head with his weapon and knock him out, which in turn, saved his life
Garrus © RevanAC
Lombaxes © Insomniac Games