When Shining Armor got back, the princesses noticed a difference in the way he walked. What really got the princesses thinking is what caused this change. They discovered that he too also got a second cutie mark. Shining Armor had gotten a yin yang symbol for his second cutie mark because now he is a master of both pony magic and chaos magic. Twilight had an eye that glowed. The princesses tried to figure out what caused this change.
The next morning, Shining Armor and Twilight discovered these new cutie marks and were just as curious as the princesses as to how they got them. Shining Armor walked as silently as a ghost. When he walked, he seemed to glide across the floors.
Shining Armor actually startled the princesses quite a few times with his powers. He was more powerful than both alicorns. He is a master of both magics. He is never vulnerable to magical attacks.
Twilight also was different. She was prone to seeing the future at random places and times. Luna is trying to help Twilight control her new power. Luna and Twilight spent the next several weeks working on her mastery of her new power.