Episode 983 Kid is the one that first sees the giant sword. Can’t find the clip right now since toei takes everything down
I found the clip you were talking about, correct me if I'm wrong here.
I can see where you're coming from here as I have a bit of an editor's perspective on this. It can be said that the shots here is about the reaction to Onigashima in general, but I think the placement of a couple of shots are interesting.
Shot #1: Kid smiling and saying "There it is"
Shot #2: A very slow tilt down where the sword is very clearly being shown.
While Kid is actually reacting to Onigashima, the placements of the shots puts in the viewer's mind the connection between Kid's magnetic powers and a giant metal sword so it works as a potential hint.
This idea is a part of the concept of "The Grammer of the Edit," which is placing shots in such a way that it helps tell the story. The connection that these two shots made is a good potential example of this if Kid does use that Big Ol' Sword.