The painful welding you're thinking of is either Mig or stick welding, which creates very very hot sparks that can easily burn through clothes and require leathers and are also fairly noisy processes. This guy is gas welding; it's totally silent and very zen. Those sparks don't really hurt and the skill in this process is producing a quality weld while in an awkward position which is quite difficult.

Having assisted a welder, I know those sparks could sting any bare skin. If one wore something like gloves, for example, the hot sparks could fall inside them and get trapped.

My grandmother was a single mom during WWII, and set out to find the highest-paid work available in the local shipyard (Evansville, Indiana). She was an overhead welder since it paid twice (or better) what secretarial work got you. She was good at it, too, and kept it up in various factories till my mom & her brother were in high school, I do believe.

I can confirm it: Overhead welding is tough!