A
Although your own example doesn't get to cover this because what scars from Sakazuki's attack is his magma, while what scars from slashing Kaido is still the slash, not the haki by itself. But who cares at this point.
btw... AO-fucking-KIJI left a lot of scar on magma kojo and he doesn't use swords.... and he left scars on magma itself so dont find excuses because its a punch... you punch strong enough will leave lasting damage....