Your level does not change once you start a canon thread.
You can only have
two +20 substat boosts whether you get it from the store of defeating an NPC
@Oreki Mihawk's sword does not work like a DF. If the stats are old from when Larsi first wrote the RP then it will need to be updated before you start fighting him.
I'm sorry, but idk who told you all of this misinformation. Please don't take any of it the wrong way.
If you think you have a shot against Mihawk right now you are mistaken. You can still write a story around it if you want to. Or you can wait until you level up a bit and come back later.
Used to be 3 Marines and 2 Pirates lol