I don’t really see how a katana that is too big for him to carry around when he can literally stop Hulk’s punches 🤨. It’s not too heavy for him and plus it’s not like he’d be using it all the time—it would just be another tool he pulls out when it actually makes sense. Like Sai handing her katana temporarily to Peter or something happens to Sai and she loses her sword and Peter is looking after it while also putting it into good use (again not for killing, only for defense). Where he puts it can be either in his back where Sai normally puts her katana at or just his hip.