I kept trying to convince my cousin to spar me like this but I think he is afrraid of me.

This looks like a lot of fun with sticks & a shinai but if someone ever came after me with a samurai sword and all I had we're two machetes I'd probably run away fast as I could.
It is almost universally recognized that running is the better solution to fighting when the option is available. Even if you have a firearm and he's coming at you with a sword, you're generally better off avoiding the confrontation in the first place. That said, if you have someone you must protect (family, etc.) that changes the whole ball game.