The witness was given 'blanket' protection from prosecution. [=the witness would not be prosecuted for anything]
The job was her 'security blanket'. [=the job was the thing that made her feel safe and secure]
A 'blanket' of gloom spread over the crowd when they realized their team would lose.
(..) You use them as a punch line. I have neither the time nor the inclination to explain myself... to a man who rises and sleeps under the blanket of the freedom I provide... and then questions the manner in which I provide it! I would rather you just said thank you and went on your way. (..)1992 A Few Good Men
(..) and my palms were sweaty... and I'd forgotten to use the resin like we were taught. What happened? That night, the guys in my squad threw a blanket over me... took turns punching me in the arm for five minutes... then they poured glue on my hands. And it worked too, 'cause (..)1992 A Few Good Men