User blog comment:Water Dragon Slayer/DREAM BATTLE CHRONICLES: FOURTH MATCH!/@comment-11966702-20130807140132/@comment-7418318-20130808142653

The eyepatch doesn't proof anything.

While it might be as you say, he might just as well have lost his real eye early in his live and only replaced it decades later with the demon eye long after leaving Fairy Tail, or anything in between.