The Bronze Armors' design change every time they're repaired/revived with blood. In the manga it happens 4 times for Seiya and Shiryu and 3 times for the other main characters. This is because both Seiya and Shiryu are the first Saints that damage their armors to the point of needing a serious overhaul. However, even though this incident is portrayed in the anime, the Dragon and Pegasus armors don't change in any shape or form after their first restoration.