That's a good idea for more in-depth character customization. And maybe different types of mages would have different tatoos; destruction tatoos and healing tatoos. idk just an idea
Or we can take a Crips and Bloods approach, every factions has unique tattooes the player only can get there and through quests you can get new tattooes
silly idea, but I kinda liked it too
just don't fits the elder scroll's series with tattoo artists all over the place, but when the player makes the character, add warpaint in many formations and images