It's still not the mystery you're trying to make it.
Lord of Chaos Prologue:
Dark lord to Demandred: "The weak fall away. Who betrays me shall die the final death, Asmodean twisted by his weakness, Rahvin dead in his pride, he served well yet even I cannot save him from Balefire."
The...
It wasn't just a glossary explanation, when Graendal is speaking with Shaidar Haran in ToM he specifically blames her for killing 3 of the Forsaken. The other two being Aran'gar whom she leaves to die to Rands' balefire, and Mesaana who is defeated by Egwene (in part because of the dreamspike...