Unless there is something "special" or "different" that happened in your mash or your fermentation I would suspect that the beer is done. You can try and add the yeast but I doubt you will see much, if any, difference as a result. 1.084 is not that high of an OG.
I have only been brewing for 1 year and your post lit a light bulb for my brain cells to see a little clearer Fred.... This was the first brew I made which was intended to end up with this high of a FG. I mistakenly thought by adding the champagne yeast that it would reduce the 1.022 gravity down further. I now realize my original yeast had indeed done their job by converting all the fermentables while leaving only the non-fermentables and a 1.022 FG. Since this was not a 'stuck' fermentation, by adding the champagne yeast to this non-fermentable wort for an additional 14 days, I was just wasting the yeast, right? Oh well, it did give the secondary an additional 14 days of aging..
I bottled this batch yesterday, and sure enough, the hydrometer still said 1.021 - 1.022 .....