Trained Herald/Renegade and now Vindicator but trouble with short bow

[wrong.1950]

Recently returned to Gw2 and am confused.  I trained all the above and recently with the EoD expac, I trained Vind.  When I started back, I played Renegade with Short Bow.  When Halloween started, I chose my Herald build but for some reason, I am unable to choose the Short Bow.  I thought the Renegade short bow was bound somehow to the the Renegade build so, instead, I bought a short bow off TP and tried matching it with my Herald. No.  That didn't work.  The short bow is greyed out on my equipment list.  What am I not doing right?  Can I just have the one short bow for both builds or do I need a separate for Herald?

[Shagie.7612]

You need Secrets of the Obscure, and then you have to do a bit of the story (or buy the unlock from WvW) to unlock Weaponmaster Training.

[wrong.1950]

I was almost going to open a ticket on this but will now look into unlocking in WvW.  Weaponmaster Training.  Ok.

Thank you very much.