The hammer that Fisk shows Maya is not the actual hammer he used to kill his father. It's a different type of hammer. As shown in Daredevil, the murder weapon was a claw hammer, and his mother presumably got rid of it while disposing of Bill's body. The hammer Wilson shows Maya is a ball-peen hammer. This is another example of Fisk's manipulations, as it's clearly just a common hammer that he acquired with no significance, and he plays it up as if it is the murder weapon to demonstrate his "trust" in her, while not actually giving her a key piece of evidence against him in case she brings it to the police. She would have no way of verifying if it were the same hammer, or even same type of hammer, so in his mind why even bother getting the same kind.
Trusting Maya:
As noted by Maya, for all Fisk's claims about caring for her, he never bothered actually learning ASL. This is interesting since Daredevil season 1 showcased Fisk understanding Mandarin and Japanese to conduct business with Madame Gao and Nobu respectively (while pretending he didn't know the languagesto create an excuse for James Wesley to be present). This further highlights how little Fisk actually respects Maya and how he simply sees her as a tool or extension of himself.
There are a few implications that Fisk does understand ASL (he definitely knows a few of the more basic signs, at least). This still fits with his trust issues: No matter how much he claimed to love Maya, he was still hiding his true intelligence from her. Note that this does not contradict his earlier appearances; remember that Wesley didn't know his boss spoke the languages he was translating for. Fisk lies to everyone until he is forced to reveal the truth head-on.
Additionally, Fisk revealed his true role in his father's death toBenjamin "Dex" Poindexter. There's an argument to be made that he did it to spare Maya's feelings, but given that he tries to pin blame on her for not objecting to his work, it's more likely that his true feelings towards (and distrust of) Maya are seeping through.
The silent-film vignette in episode 3 works not just for a story set in the 1800s (when celluloid had just started), but for a show whose main character cannot hear.
A casual analysis of Daredevil's fight against Maya shows that she is hopelessly outmatched - he's barely even trying and most of the hits she gets in are because he didn't try to keep her from landing them, and he still absolutely dominates her and has her on the back foot for the entire bout. This is because he can sense from her vital signs that she's in way over her head, doesn't want to be there, and is terrified out of her wits - he's trying to fend her off rather than win because he knows she's someone in a situation she doesn't belong in, rather than a hardened criminal.
Fisk had his sign language interpreter killed in 2021, two years before half the universe was snapped back into existence. If that poor woman had any family members who were dusted, they definitely blipped back to find that she's no longer around. Who knows if they even found out she was murdered?
The fact that Fisk and his empire were still active and causing problems gives a whole new perspective New York City's barren and struggling state in Endgame. The few people who survived and stayed in New York not only had to deal with scarce resources and the loss of their loved ones for five years, but they also had to deal with a ruthless mobster who likely was taking what few resources were left and accumulating them for himself.
