During the Daredevil arc "The Devil, Inside and Out," fellow vigilante and occasional ally Matt Murdock AKA Daredevil is slowly breaking down while imprisoned at Ryker's Island. Frank is sitting a diner reading about Murdock's almost Punisher-like activities in jail. Deciding that Murdock needs a reminder of who he is, Frank gets up, heads outside, and casually breaks the neck of a pimp beating on one of his prostitutes, advises the girl to get clean and out of the life, and surrenders to a nearby police officer. Just to go help Daredevil.
Later, during a prison riot intended to kill Daredevil, Frank calmly waits reading a book in his unlocked cell for DD to come get him...though any thug that dares take a run at him ends up in a pile of bodies outside the cell. He subsequently uses the riot to break himself and Daredevil out...by pretending to hold "helpless" blind lawyer Matt Murdock hostage at gun point, simultaneously springing them and creating a little more doubt that Murdock is Daredevil (which he's on trial for).
Frank jumping out of a plane without a parachute from 35,000 feet up.
Later in the same series, Frank goes undercover at an Auction of Evil. When, after allowing himself to be captured, he escapes and kills the overly-confident thug who was trying to beat some information out of him...