Forgive me if I seem dense but I don't quite understand how Jasnah could have faked her own death. She's not a Lightweaver so it wasn't an illusion.
I read a suggestion where she Soulcast a copy of herself--but that seems like it would be really difficult, since she'd have had to also do the clothing, jewelry, etc. If she had time to soulcast something that complex, she could have just as easily soulcast the attackers into flame, like she did with the thugs in the alley during WoK.
Maybe the transition into Shadesmar saved her? Do you bleed or absolutely need a physical body there?