Eh, I feel too little progress. Also it seems to me this is a skill someone in the kingdom of power should also have.. Not mastery of but the basics.
And.. It's a manga. They had to say they are better
That its a manga does not excuse it for lying.
Anyway, as such not really. I doubt any of those young bodybuilders recruited into the kingdom of power would have the knowledge and skill. It is kinda obscure, perhaps mainly possesed by survival nuts and geologists?

If they are smart though, then they might manage to find some of the metals that dont corrode in the ruins of a city. Alluminium Should be a viable pick. Or Bronce.

Alternatively they can just stick with spears. Those are a superior weapon anyway.