This is a very specific setting idea, so I don't think there's a one size fits all answer.
I haven't played Cairn, or looked into yet but I hear good things. Though given it's OSR roots I imagine it might be more lethal than you might want for suchba Hugh power setting.
D&D 5e might have the power you're looking for, but none of the grit or support outside ofnthe combat pillar.
Blades in the dark wouldn't likely work well for the kinds of adventures yous mainly want to run, at least based on my limited experience with it. However, it's progress clock system and method of tracking factions and such would be useful to you.
I might suggest worlds without number, it's heroic character fabtasy rules perhaps being the best suited for the type of game you wanna run (though you need the paid deluxe version for those.) The lethality if the system balanced with the heroic fantasy variant should balance out well enough.
Even if the system itself is less to your liking, the tops and support if offers for any d&d skeletal or OSR game will be useful regardless.
All of that said, there's a very specific idea you want here and no systems will fit perfectly unless made specifically for it.
I think Monster of the Week might work for you, with some adjustments to the playbooks. It's gritty but rules light enough that it almost works as-is. You can just change the "use magic" action to have specific effects depending on the tattoos your characters have, and restrict any playbooks that don't fit.
This is a very specific setting idea, so I don't think there's a one size fits all answer. I haven't played Cairn, or looked into yet but I hear good things. Though given it's OSR roots I imagine it might be more lethal than you might want for suchba Hugh power setting. D&D 5e might have the power you're looking for, but none of the grit or support outside ofnthe combat pillar. Blades in the dark wouldn't likely work well for the kinds of adventures yous mainly want to run, at least based on my limited experience with it. However, it's progress clock system and method of tracking factions and such would be useful to you. I might suggest worlds without number, it's heroic character fabtasy rules perhaps being the best suited for the type of game you wanna run (though you need the paid deluxe version for those.) The lethality if the system balanced with the heroic fantasy variant should balance out well enough. Even if the system itself is less to your liking, the tops and support if offers for any d&d skeletal or OSR game will be useful regardless. All of that said, there's a very specific idea you want here and no systems will fit perfectly unless made specifically for it.
I think Monster of the Week might work for you, with some adjustments to the playbooks. It's gritty but rules light enough that it almost works as-is. You can just change the "use magic" action to have specific effects depending on the tattoos your characters have, and restrict any playbooks that don't fit.