Uh, the story is I think the usual for Redchet:



* Redchet sketches something amazing and offers it as a YCH commission

* Cloudzapper in this case won the auction and got his character inserted





As for bridle and bit - I think those actually go way back to Equestria-Prevails, who was one of the first major artists to draw ponies in armour. It was part of his armour style/design. And he inspired armour designs ever since

