Hello, I'm not a secure coding expert, so my point of view is more from a developper view.
> + What functionality should the accompanying libraries support > (e.g., encryption, access control, etc.)? In my opinion, it's the most important things for a languages, something to easily validate user input or to encrypt password are a must have. And the other good thing with a good base library is that the user don't need to re-develop his own one. And it's easier to extend, to maintain and to import the security of a main librairy instead of a lot of 3rd parties library. -- Fabien, sorry for his english.