Tattoo Magic
We see tattoo's as new socially acceptable things instead of taboo's like they were several years ago. Several years ago being reserved for murderes, freaks and bikers. Now every wet noodle that turns 18 or has access to a tattoo machine wants this very old body modification done. It's permanent but not a hole in your flesh so people are more likely to get one. Well I suggest that we get them for a damn good reason. Usually people are more likely to get them because they mean something but there's ******** out there that just want to get one to be cool so they get one right out of the pictures on the wall like most idiots. Let's turn it into something useful...
Sigils
Sigils as tattoo's can be more powerful than the normal way of doing the sigil. You can have the physical subconcious reminder on your flesh to trigger certain aspects of the purpose of the sigil. Of course we aren't gonna get effects like terribly increased strength or any of that bullshit but things like time based effects have been proven to be effective and working. They can also be the base for using your godforms in combat or in general purpose areas.
Weapons
In reference to the soul stealing weapon I am getting several sigils placed upon my forearm which dictate the process of attack the weapon will use. Sigils desinged for attack against specific type targets or added to an actual weapon will make the weapon way more effective. IE a godform attached to a hand tattoo in which the same inscribing is upon the handle of the weapon used.
Defense
Think shields. Now make a tattoo/sigil that represents a shield of some form and what it is meant to shield you from. Actually shielding you from bullets and expecting it to be body armor is right now almost absurd. However you can make yourself appear at far distances "blurry" thus making it harder for someone of average shot to hit you.... Yep now you're thinking. Shields against bad spirits as tattoos have been placed upon human skin since the art was invented so don't think that you are doing something new.
What I'm saying is that no matter what the tattoo looks like if you have a subconcious attachment to it that you want to produce an effect then it becomes tattoo magic.