It took me a long while to connect them, but two different episodes that I can name have the killer handing Columbo an object as a kind of "surrender" - "A Matter of Honor" (with the flag) and "Short Fuse" (with the honor society medal). Do any others end that way?

on his way to the slammer Findlay Crawford autographs something for 2 fans . not given to Columbo but nevertheless somewhat of a token.

And I wonder if Columbo ever kept the tongs that were given to him by Prince at the end in Ashes to Ashes

In "Murder by the Book," could giving copies of all of Mrs. Melville book's be a form of surrender? Columbo read them and could tell how Ken set up the first murder. Also, when Mr. Glesko went for the camera in "Negative Reaction."

Paul Galesko is not handing Columbo anything. He is in fact being his own arrogant self and by doing so, he gets caught Galesko thought that he would never get caught.

Findlay Crawford was arrogant because he asked Columbo if he could put him in a prison where they will need a conductor for an orchestra.

A reversal on this might be when Columbo brings along a dessert wine to share with Adrian Carsini when he corners him.

Carsini knew it was over the second his secretary confronted him.

Short Fuse always makes me wonder if Columbo has a trophy case for the crimes he's solved like Batman has in his Batcave.

What do you mean by Short Fuse? The cigars and cigar box?