Halima as Sheriam's attacker isn't really supported.

 

You'd think that Sheriam's POV would be "...she was wrapped in something she couldn't see..."  If she was attacked by someone using Saidin, which Halima would have.  Although it is possible that since she was under duress at the time, she didn't notice.

 

With Lelaine's continuing ambitions for the Stole made abundantly clear to Suian in KoD, I believe it was she who is blackmailing Sheriam and that Lelaine is black and Sheriam is not.

If Lelaine was black, either Delana would defer to her, or the other way around, and Hamila would go with youever was highest, the same as Mesaana does with Alviarin. nor would she be eager to take Egwenes place, because the chosen like the set-up as it is.

If Lelaine was black, either Delana would defer to her, or the other way around, and Hamila would go with youever was highest, the same as Mesaana does with Alviarin. nor would she be eager to take Egwenes place, because the chosen like the set-up as it is.

 

Remember that the BA operate in groups called "Hearts", groups of three, with each member knowing a single person outside of that heart. So the odds are that even if Lelaine is BA, Delana would not know it. I don't think Lelaine is black but neither does she need to be to beat Sheriam, Elaida showed that in New Spring.

 

I will enjoy seeing Hurin back in the final book, I too hope he becomes a new Hero of the Horn

Indeed, Delana and Lelaine may well have no knowledge of each other.

 

I've always liked Lelaine for a Black--when she and Romanda were first introduced i thought one of them must be, and Romanda has been proven not to be. From there the easy way she switched back and forth between being nice and sweet to being a complete harriden revealed to me a woman who hides her own nature as easily and instinctively as breathing. And did anyone else notice the way her actions mirrored Taim's as the instigator in seeing to the Aes Sedai/Asha'men bondings....

 

And beyond that, with Delana and Halima gone, the Black needs someone high in the Rebels--so it makes sense from a literary perspective.