Ethelrida knows all the dirt on Nurse Mayflower, who just got arrested for essentially being a serial killer. She also saw the nurse with Josto. Given that she knows the nurse killed Donatello, with the ring it’s easy for Loy to convince the New York mob that Josto ordered her to kill him. Especially with them already being irritated with Josto, and Gaetano being dead (knowing that they had beef but not that they’d resolved it). Having the ring just adds to the proof.

My guess is that Loy wins the war by having NY come in and clean everything up, but in the end he gets killed by either Leon or Zelmare. That would be the perfect callback to the turtle story from the last episode - with Leon and Zelmare both being turtles that Loy stepped on to maintain control as king.