"Naming: A better name for "Writ of Exemption" would be "Writ of Manumission" -- because 'manumission' is exactly what it does."
I agree that "Writ of Exemption" isn't the best name, but I had to look up what "Manumission" is, and I would guess that most other people are not familiar with that term either. Good communication is not about impressing people with obscure vocabulary, it's about using words people understand.
I would suggest to just call it "Writ of Freedom".