Would it be possible to enable GBC-style button mapping for items, where the Sword—and Shield, but I'm alright with leaving that one as it is in Zelda 1—is grouped in with the tools you acquire, and any of them can be freely mapped to either A or B?
Alternatively, would it be possible to simply set a non-Sword item to be mapped to A, or a Sword-type item to be mapped to B?
The reason I ask is because I was planning on making a quest that features the axed "Sword or Boomerang" choice that was present in an early prerelease iteration of Zelda 1. My thought was that whichever item you chose at the beginning would be mapped to A—and would be buffed to actually be able to deal minor damage, in the case of the Boomerang—while you would get a weaker version (stab-only Sword, regular Boomerang) of the one you didn't choose later on as a regular tool that can be mapped to B.
There doesn't seem to be a field in the editor that lets you change which button an item goes to; I'm assuming that Sword-type items always go to A, while all other items always go to B.