Amaryllis had been observing Aurea torturing Uriel and it was effective because angels weren't like humans who had a real physical body, they were spirits. Aurea's power was specialized in dealing with souls and spirits, but although she was capable of hurting Uriel, Uriel didn't feel any pain at all.
Both Aurea and Amaryllis already knew that it was impossible to get something from Uriel because of that. Her personality and lack of emotion made her impossible to crack, and her loyalty to The Lord made her endure everything.
Luckily, even though Aurea couldn't get anything from Uriel, Uriel was powerless. Whatever Elena did to her, she managed to lock and disable Uriel's powers, and that made them at least feel at ease.
