EVEN BETTER HAHA he literally has Camael, Barachiel, Sabriel and Gabriel's names tattooed in with pretty patterns around it but yeah his tattoos light up when he uses the blessings and unlocks them so they will stand out a LOT in the dark - it doesn't last the entire time but it'll be obvious enough at the start. his skin has to be visible for them to work, so either he has to have his shirt off or it rips half of the cloth away so c8 goodtimes.

here's an example: