Yeah, Erin should have taken the chance, even if she had truly died, it would have given everyone else the ability to fight back.

"I...most of it. I could hear, see, feel."

The empathy still worked, Tiamat simply didn't care and left Valdis to feel it and remain unable to act.

"She didn't even hesitate to torment people, to use their own feelings against them."

Valdis keeps the tears away, those are for later, when she is alone. Now is for Erin and whoever else needs it.

"It's painful to know that I am also capable of that cruelty, it's not just her."