Again, its not really regeneration you're talking about here. Its about them just not taking crazy damage to begin with. I used the Reiju thing because getting shot a singular time took hours minimum to heal from, if you can get past the exoskeleton and do legitimate damage (the Candy Jackets were just an example of a weapon made to punch through tough armour; its not like they are the only thing capable of that). And in the context of this fight (and even tbis chapter), Sanji has gotten stabbed multiple times by Longinus, so even if he can easily brush off the times he's been slammed through buildings/donkey kicked (pretty fucking rude of Killingham, that one), I don't think he should be healing from the stab wounds in the context of this fight?