To me, both of those are plot devices, not powers.
The devils trap is worthless if you can't lure the demon inside. But if you can lure a demon inside, it stays there, no question asked. So I would work with that, having a contest or a social conflict talking while luring the demon, and "trapped in a devil trap" is simply the taken out result. Or you could do some sort of ambush/stealth/deceit thing to make the demon fall for the disguised devil trap. And whenever a devil trap breaks, that's a perfect example of a compel, I think.
The tattoos are mainly there to get away from the "brother gets possessed, other brother forces demon out, rinse, repeat" routine. The two were possessed quite a bit in the early seasons, but that gets boring after a while. So the tattoos are less a power and more a "we've done this more than enough, let's focus on something else" sort of thing. A social contract for the table, what the game is going to be about in the future. And if everyone at the table is sick of the "brother gets possessed" storyline, it's an easy fix to say they can no longer be possessed, because... tattoos!
