The two weeks is generally a courtesy notice. It's important if you want to remain on good terms with the previous employer and people in that business. Eleven days is not bad at all. As an employer I would understand, but would expect some communication about the 8mo/1yr situation.
Your employer paying you to sit at home and read is definitely training. Your reduced effectiveness at work because you weren't up-to-speed is why I presume you weren't hired at an up-to-speed wage - you were learning on the job. Eight months is substantial, but at less than twelve, you didn't live up to your commitment. Did you communicate with your management before giving notice? That's often enough to smooth these situations.
I haven't held wages in these situations. Delayed, but not held. Usually the worker is becoming known for their patterns, hopefully learning lessons along the way. You could file against the employer which may follow you. You could call it a mistake and let it go. Or, if the amount is substantial, negotiate. 8/12 = 66% and don't burn the bridge?
Your largest assets at work are the relationships you maintain. Try not to make "largest assets" into something negative.
