What to do for the horse in costume Cl, Its really stumping me...?

For the local fair, I am entering costume cl, I know what I am dressing up as, But for the Horse Im not exactly Sure. I am dressing up as Arya Dr�ttningu from the Movie, Eragon. In was condiouring an armour plated plate and neck sheild, but Im not sure what would win me something in the show arena. Is there any help for a girl like me, Oh yah My Horse is a 16.2 hh Dark Cherry Bay Thoroughbred.