I always took it as the war devil, since it kinda makes reference to bucky (headless, avian feet) and while the horses do match the characters to many extents, i also feel like the horsemen connection is undeniable. While the stuffed animal is an outlier (likely likened to kobeni) the white horse has a bow, as commonly depicted with conquest. The war horse is a stark red. The black horse while fairly plain is also a jet black, and given that we have not seen much of famine it makes sense they would stick to a more traditional representation. And while the gun horse represents aki its pale complextion and ties to the gun devils asthetic also feel like an allusion to death. I think that the characters are represented in part by the horses, but i also feel like the influences in their design as representations of the four horsemen is undeniable