NeverarGreat said:

When he throws away his lightsaber, it may be as much for Anakin as it is for the Emperor. It's as if Luke is saying "See father, I don't fear this man, and neither should you."

I read that more as, 'I choose the light side over potential death' than 'I don't fear the emperor'. Or, perhaps, a hybrid 'I don't fear death, I fear the darkside' or even 'Because I'm a jedi, I'd rather die than join the darkside. There's nothing for which I would join the darkside'

It's him restating, 'I will not fight you.'