This seems like a really weird and specific restriction. Is there some kind of bad interaction with tattoos, or is it bugged out?

(I ran a few characters through the academy quickly - a healer, a paladin and a shaman didn't have it available at all, while a ranger and warrior did. All other variables were the same.)

It's priced for characters who really lose out badly by giving up a hand.

If you want it on a character of a different class, you can pray and someone will probably be willing to give it to you, but you don't get anything for it.

That I am very upset that you changed the name of my flaw suggestion from Single-Handed, as in I defeated you single handedly, to One Hand.

I actually forgot you get a few edge points for flaws. I wasn't thinking about that at all, it was just part of the character concept.

I did try praying but nobody answered. Next time I roll him I'll give it another try, thank you

I believe it's based on the D&D rule of priest classes needing to hold their holy symbol.