What is this ? We are discussing this mode related with Redsn0w. When you are using Redsn0w this is like same DFU mode. This mode used to restore custom IPSW via iTunes. So when you restore custom IPSW you can not use normal DFU mode. When you click Redsn0w lateset tool 0.9.10b6 “extras ” you can see Pwned DFU mode screen shots as follows.
If you try to restore using normal DFU mode you can find error in the iTunes. So restore custom IPSW this is important.