Re: is it safe to sand off a guitar's finish?
[RELIC FLAMESUIT]
The most realistic way to do any relicking is to use exactly what would cause the wear in real life.
If you want to do buckle wear on the back, use your belt buckle. Not something like a belt buckle; A BELT BUCKLE.
If you want to do forearm wear, however, you may not have the time or skin for it. In these cases, you want to use the closest thing you can find. You can cheat by sanding an area SMALLER THAN THE AREA YOU WANT TO BE AFFECTED, then finishing it by rubbing your arm or something like it against the guitar. Commonly used finishers are old blue jeans and leather.
A legit guitar takes decades.
A bad relic takes a day.
A good relic takes an amount of time somewhere in between.
Plan old work, elbow grease, time, exposure, etc. - there's not a quick way to get around it, only quicker ways.