What level do you need to be to kill Duke in ELEX?

In The Fort?

Need to get a conductor, for the airship or whatever they call it, but I can't even make it to the mech. Need to level up.

How much XP to you get for killing Logan? That's the Duke's actual name.

The outlaws are dicks, so I'll get rid of them. Maybe. Probably need to level up more. He has guards and crap. He might only get stunned if you try to kill him.

Will I owe William money for killing Logan? Just kill William too.