I'll have to side with EdgeTheLucas on this one, giving Lucas a non-canon weapon is definitely farther than they've gone with any other character, so I'm looking for a confirmation before believing it's official. The Master sword having a slightly different design betwween games that they didn't bother changing or Tink getting his starter sword doesn't really set a precedent, in this case. It also would seem to me that just pasting a sword onto an animation for swinging a stick isn't really the PMBR's style. It might even require changes to sound effects (to reflect the fact that it is cutting and not bashing) that could normally be impossible for the alt costume engine.
That said, if it is official, and if this is potentially all the Masked Man we'll get, I won't exactly complain about that. I'd rather have the sword with the costume than not. It would also be awesome if they gave the OU version of the attack an electric effect or something. Not sure if I saw that at all.