It might be beneficial for some x360a users to know what constitutes as a "retry" in Ninja Blade.
In the purpose of science
I died many times in mission two, however, instead of "loading last checkpoint" I always used to quit. Sure, I had to start the level again but the stats didn't seem to take the death into account.
On the try where I completed the level I died twice and reloaded the checkpoint (simply because I wanted the torture to end). When I finished, the stats read two retries.
So, maybe that is a sneaky way to get around this difficult achievement without starting a new game every time or multiple saves? Just an idea.
Edit: This is for "Your Work Is Done".