If you don't want to sell it you could always find someone to desynth it but, as someone that desynths stuff frequently, the odds are fairly small to get the whisker back that way. I'd say maybe try to sell it on marketboard.
But as others have said, next week they are adding a new recipe for a mog whm cane. It was mentioned before the patch notes... like a month ago in a live letter I think? I mean, it's not like everyone watches those or reads the translations (if there is one) cause it's so early in the morning when it's on.
Seriously though... while I'm not sure the vendor can take the one you got for trade like the other person mentioned (I'd check on tuesday to make sure though), why not try talking to a GM and see if they'd trade it out for you as your one time item replacement? It's kind of a grey area but, if you get the right GM they might feel comfortable doing it. Just be nice to the GM! Being nice goes a long way to getting what you want of course. Trading out items that were gotten in error has been a MMO staple for a long time. Of course you wouldn't be able to trade it out till thursday since that is when the new recipes come out apparently. I know tuesday would make sense since that was when the maintenance is but thursday is the crafter script reset weekly time.
It's worth a shot anyway. It's not like a GM would be mean about you asking. It's a mistake anyone could make really.... It's the same as accidentally buying the wrong tomestone item to me anyway.
