Here is the one secret achievement you can unlock in Gears of War 3 for theXbox 360.
Check out my other guide if you’re looking for the full list of unlockable achievements in Gears of War 3.
Respect for the Dead (5) – Your respect for the dead earned you access to Griffin’s special weapons stash
Tip: To unlock the Respect for the Dead achievement, in Act 4: Chapter 1 “Ashes to Ashes”, you must make it through the level without shooting, hitting, or otherwise touching any of the Ash Bodies.
If you do this properly, once you reach the stranded camp, the achievement will unlock, and a weapons locker will be unlocked for you.