The first time they received the Sacrament, they were told they would be blessed for doing so. This time, after partaking of the Sacrament, He spoke more specifically (and allegorically) about the blessings of partaking of the Sacrament (8). They not only partook it in remembrance of Him, but He said "he that eateth this bread eateth my body to his soul; and he that drinketh of this wine drinketh of my blood to his soul;"
It solidifies the correlation between the Sacrament and the Atonement. When we partake of the Sacrament, we are not only remembering Him but inviting Him into our souls - - by taking the Sacrament we make Him a part of us.
He also stated that when we shall do this our souls shall never hunger nor thirst, but shall be filled. He wasn't referring to hunger for the bread He brought, but the nourishing word and affect the Sacrament has on our souls.
Then He spoke about the prophecies regrading Himself.
I wonder how many of the Nephites were sitting there thinking, "What is He saying?" I'd say it's safe to say that most people are thinking that.
It was interesting to note that He gave them the deeper doctrine AFTER they had been sufficiently prepared by the hearing the teachings and participating in the ordinances of Baptism, receiving the Holy Ghost and partaking of the Sacrament.
That's how Heavenly Father and the Savior work. They teach line up line, precept upon precept.
That's how we learn. That's how we grow.