If I were a 2-liter soda pop bottle and this guy came at me with his sword, I would fear for my safety.
I would be justified in shooting him in self-defense, if I were a plastic beverage container filled with liquid.
If I were just a regular armed citizen and he came at me with this sword in that outfit, and especially if he was holding his sword backwards with the blade folded back along his forearm and extending past his elbow as you might hold a dagger...
... I'd shoot him just out of general principle!!!
(Fast-Forward to 5:30 mark on this scene from Pulp Fiction-- Vincent says he is going to shoot some doofus robber on g"general principle")