Managed to find a small but notable bug, and that is the fact that you can't give yourself revolvers as Engineer.
Attempting to do so will toss an error message in the server console stating "Attempted to create unknown entity type tf_weapon_revolver_secondary!"
So after a little bit of digging, it appears that the Econ Data plugin, which includes the stocksoup include files, contains a bit of code replacing the "tf_weapon_revolver" class with "tf_weapon_revolver_secondary" if engineer gets a revolver.
I am assuming that tf_weapon_revolver_secondary outright doesn't exist in TF2, in which case you'd have to not only question yourself why it was added in the first place, but fork the project and remove that tiny piece of code.