A chanfron is a piece of horse armor. It's placed over the horse's face, leaving only the eyes and nostrils visible. Flanges often covered the eyes. It was fashionable at times to place a forehead spike on the chanfron - this appears to be decorative. One chanfron from about 200 BC has horns that rather resemble Loki's headdress in Marvel comics.
An Italian chamfron from the 16th century. Image source Walters Art Museum (where it is on display).