Pip is terrified when he sees the file again, even though nothing really happens. It foreshadows danger ahead. He does not want to be reminded of the frightening events with the convict. This chapter ends with him having nightmares about the file and screaming himself awake.
“He stirred his rum-and-water pointedly at me, and he tasted his rum-and-water pointedly at me. And he stirred it and he tasted it: not with a spoon that was brought to him, but with a file.”
The emphasis on the word “file” is unmistakable, of course. This is when Pip realizes that he has a problem. He continues:
“I knew it to be Joe's file, and I knew that he knew my convict, the moment I saw the instrument. I sat gazing at him, spellbound.” (Chapter 10)
The iron showing up again is another story. Mrs. Joe is attacked, and the iron is found at the scene. Joe notices that it was filed away long ago. Pip is worried because of his connection to the file.
“Now, Joe, examining this iron with a smith's eye, declared it to have been filed asunder some time ago. The hue and cry going off to the Hulks, and people coming thence to examine the iron, Joe's opinion was corroborated.” (Chapter 16)
This is important information, because Pip learns that one of the two convicts got away and one was arrested.