This ornament can be / is / may be awarded by Guides at Guide Events. (I do not actually have one, just seen a link.) The Item restriction says "Bows Only" -- which is very odd for a spoon (there is also a Fork and Knife, that re not Bow Only). When you "preview" this item, it appears in your Primary hand. So clearly, the game does not believe it is a Bow Only Item. I think the restriction on this item is supposed to say "Weapons Only" -- like the Fork & Knife versions do.
Well, the fix didn't seem to work. Preview the item and it appears in your primary hand. All other bow only ornaments appear in your off hand.