My guess to this wonderful charm is that it is just like the Temple it self. Remember that ToV is not complete. They put it out too early that explains a lot of the non equipable items and bugs there.
I can't back this up w/ a link to the post, but, being that my main is a bard, i remember seeing in a post by Abashi, or Absor, that kerrans would most likely be able to play bards. I already wish my bard were a kerran... I wonder if they'll give bards & rogues another one of those excellent illusion masks for kerrans too.
Why would they have given it stats if it wasn't meant to be equipped? Also, there's other necklaces with similar stats, and all of them have ALL races. Probably just a database error. Another quest item in ToV which Legacy of Steel got had a similar problem - was listed as HELD, but doesn't go in either primary or secondary.
Toss-up whether Quest or Not. Verant may have wisened up, put Bard in to make sure it goes to the right person... or not. Who knows? I shudder to wonder how Verant obtained the IQ to do THAT....