Saitama left a giant crater on the moon. No, he would kill blast instantly. Blast might be very strong, but like the guy below said, it's a parody the MC will always win except maybe near the end of the story, but I doubt that as well.
@SlurpNoodle Just gonna note, expensive riot armor is pretty much completely safe against blades, and arrows. You'd have to have a bow-man with a few years of experience to even pose a real threat. Tear-gas would stop most of them, the more experienced might be able to still fight. I'm not sure...
@OP_Zed You get less muscle as well, your body gains muscle from healing, so rest is a vital part of it. I'm not sure what an ability like "Regen" would do, but this is poo-poo manga isekai.