This is my understanding on how the torch works. You aim at a weed zap it with a flame that superheats the weeds fluids which in turn expands and explodes the weeds tissues roots and all.
Well that's the theory. Never seen it used I am also interested in if it works as claims. If it does it will be the best weed remover besides my idea.
Place a long horse syringe needle on the end of the hose of a Backpack sprayer filled with water. Jab needle into ground next to weed let fly pressurized water - reach down pull out loose weed and roots.