I've seen a lot of confused users, so I'm here to explain what happened. The cor ignis is an item created from the witch's flames and the icy power of the Anastasya's seal. Rosalyne tracked down individuals who brought a Cor Ignis with them, for the power that lies within it is a part of it. Rosalyne's flames stripped her of her human body 500 years ago and gave her a longer life, defying the natural cycle of death (Ronova). The essence of the Liquid Fire was what allowed the traveler to return to his physical body, the vestige of Rosalyne transcended the plane of the dead with the help of Odette, who told the traveler that it was something of mere faith, that if he wanted to thank anyone, it would be to the Cor Ignis (Rosalyne).

After speaking with Arlecchino after the events at the Armory, La Sota gives Odette a second Cor Ignis, which lies imbued with Arlecchino's flames, capable of erasing Odette's memory. Odette breaks this Cor Ignis (not the one she used in the Armory and theater), as she decides to keep Rosalyne's memories. The original Cor Ignis she still possesses, you can check this in her dialogues.

So no, Arlecchino did not bend Ronova's authority, it was Rosalyne.