Interesting analysis and suggestion!
I wouldn't say no to more tattoos overall, and I'd especially like to see some more options regarding body tats.
When looking at the tattoos I felt like many of them felt way too "modern" to seem appropriate for FR - but then again, it is a fantasy world so whatever DM (Larian) says is a go. :]
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Regarding tattoos in general, if we're gonna be a little more abstract and flexible, I'd love to see some more style options. Like tattoos similar to the amazing design of the dalish - or body paint (... tattoos?) similar to the Slayer dwarves of Warhammer.
As for tattoos representing deities, I think sticking to themes would be easier than going individual gods (like a tree / flower / flourish pattern / growth tattoo for deities like Chauntea and Silvanus) ... Although many major (popular*) deities could have more "obvious" markings, maybe even including their own symbol. Like Selunê, Shar or Mystra.
