Okay, okay, hear me out on this one. It’s a bit out there.
Rad (Chad’s Dad) the Sworc (and by extension Chad himself) are organic swords. This is different than swords with souls, since it seems they’re born like that. Specifically, Sworcs are 1/2 Sword and 1/2 Orc.
Since the swordy part of a Sworc is hard (at least enough to stab a person), but organic, I propose that it’s made out of a chitinous exoskeleton, like an insect. Rad even has insect-like plates all over his body.
If that is true, Merblades might be similar, just on the lower halves of their bodies instead of the upper half.