Oh, splicing wire?
Mostly we use wire nuts or set-screw couplings. There are some designs for wet locations.
In old times, wires were twisted, soldered, taped for house wiring, suspended with knob and tube. Today we make connections inside boxes.
Wires will carry away a lot of heat, you you'll need higher wattage. Hopefully temperature controlled so it doesn't damage insulation too quickly.
If used in a shop rather than in the field, a solder cup could be an effective way to quickly solder connections.
I had an iron that took large diameter tips. I brazed a 1/4" diameter rod and plates of brass together to make a cup that mounted on the iron.