I didn't because I assume everyone has at least as wide a vocabulary as me, or at least access to the internet.
Well the actual reason is because it explains the middle name better. It's not Arianwen Dewi, it's Arianwen ferch Dewi. The middle name is technically part of the surname.
ALL RIGHT I WANT AN OLDER CHARACTER WHOEVER MAKES THEIR CHARACTER FROM AGES 40-50 AND ADJUSTS THEIR CS ACCORDINGLY WILL GET EXTRA BROWNIE POINTS WITH ME KBAI
It'd be amazing if as a young child he saw a tattered photograph from the old world which had somehow survived the years. He later suffered brain damage and thought he was that person.
That's a good character plot, but if it's been long enough to not hold any remains of the 'old world' I doubt a picture would have survived.
It's a nuclear photograph or, alternatively It's a photograph made out of cockroaches or, alternatively It's a photograph made using a tungsten carbide drill.
Alternate backstory: A cosplayer was trapped in a stasis pod for some reason. Fast forward a few centuries, he awakes with no memories of who he was, or is. He reaches into his pocket and there is a notepad. Scrawled in the notepad are notes on how to be a good cosplayer. Believing this to be his true identity, he sets out into the world believing himself to be a wizard.