1. Is a little archaic, and whenever you may hear it today, the first"you"is just emphasising that the other party did whatever. 2. Is nonsense. 1. You can phrase in two ways. "You just broke of the arm of your favourite toy robot". "You just broke the arm of your favourite toy robot". You may also hear "You just broke of the arm of of your favourite toy robot" "You just broke of the arm from your favourite toy robot" 2. Maybe you wanted to say something like this "You just wilfully broke the arm of you favourite toy robot. you can write 'favorite" also if you prefer American spelling.

Number 1 is correct. Number 2 is not correct. "You just broke off the arm of your favorite toy robot." is better. "You yourself" is redundant in English.