Sorry to Necro this thread. Came across it in a google search. Wisdom is a shard. In the text, the word is written as a proper noun and capitalized.
Also this WOB
Paleo
All right, regarding the 'Wisdom Shard' again. We have one quote where Hoid... I'll just cite it: "Some men, as they age, grow wiser. I am not one of those, for wisdom and I have always been at cross-purposes." Is he referring to that Shard there... or the Vessel?
Brandon Sanderson
*thumbs up, grins* ... Yes.
Prague Signing (Oct. 26, 2019)