A variable temp weller is the way to go. Mine has a separate temp controller that varies the voltage to the iron. I got one a few years back when I was doing lots of stained glass. But it comes in handy in lutherie too.
Just last night, I was using it to steam out hammer dents in my fingerboard from a couple of errant taps with my hammer. Just apply a drop of water, wait a few seconds for it to soak in a bit, and hit it with the soldering iron. Poof the dents are gone! Then a small scuff with 1500 and 2000g paper and it's as good as new.
I've also used it on a low temp setting to heat frets before pulling to soften the tiny bits of white glue I put on frets before installation.
Oh yeah.. it works on wires too.
