My thoughts for something like that would be either mustard (dijon, although it has a similar sort of pungency to horseradish), peppercorn sauce or red wine and rosemary butter (or similar)? Whipped chive butter sounds quite nice!
Unless I’m drastically misinterpreting what you’re trying to make - I assume you’re referring to some kind of sauce or flavouring for medallion steaks?
Beef Medallions
I’ve been considering making beef medallions, but I have a very strong dislike of horseradish....