Currently, the Soldering iron, as far as I’m aware, relies purely on Mechanics skill when it comes to repairing/reinforcing metal objects. This is pretty weird and inconvenient, given that the majority of metal objects that are likely to get damaged come from, or at least require, the Fabrication tree.
As it stands, it’s possible to use your level 9 fabrication skill to smith a rapier, and be completely unable to repair even minor dents to it until you’ve practiced working on cars some more. Soldering irons using Mechanics seems to be a holdover from back before the Fabrication skill was a thing.
On one hand this makes a lot of sense, how on earth can you craft something flawlessly using a soldering iron and then be utterly unable to repair said thing with the exact same tool you used to make it?
On the other hand using a soldering iron to destroy a bunch of worthless items is the best way to level mechanics initially if you are unfortunate enough to not find a copy of Under the Hood, so I would be sad to see it go for that reason
Personally I find it more dumb to need mechanics 2 to SAW a piece of SHEET METAL off a car but you only need 1 or maybe even less mechanics to WELD some handlebars to something. Actually is that stuff hard coded or is it in the jsons? Also solusphere what is that I see about a atomic cargo pants? Did your game bug out and allow you to essentially make powered pants.
A thing to note is that you do SLOWLY but measurably train your mechanics skill by lockpicking or prying any door. More specifically you can pry any closed door whether it is locked or not and it still gives mechanics experience. So I have literally trained some of my characters mechanics skill to 2 by making a makeshift crowbar and prying open a not locked closed door for a while, it was tedious as shit but it did work and all you need is either a rock/chunk of steel, a pipe and a wooden door.
The “prying unlocked door” really is a weird one.
On the one hand it looks very much like an exploit, on the other hand given than you need mechanic 2 to do anything worthwhile I can kind of justify it. Namely by the fact that so much of the stuff below mechanic 2 is something that anyone with half a brain would have learned by the age of 10 by default, so I don’t really care if there is also an exploit(-ish) way to train that up.