how do we know if he won't murder her? their ice powers are the same, both wear a magical item that grants them ice powers. both know the same spells, ice king is a ninja, so i wont be so sure that she would murder him.
My AT OC Luke has handled worse then theese two, so I am pretty sure he can handle them both.
Ice Queen's crown is one strong Arcane Gust away from being blown off her head, and one strike of one of his swords can knock of the Ice King's, plus in his Angel Form he is resistant to all frost attacks, so even thier strongest attacks are useless.