Millie knows that the Kayser Tower wasn't just designed to look like a Mage Tower. Although it is smaller than the ones made by the Black Tower Organization, she knows that all of the materials used to build this were items that Vincent had personally modified.
During these past two years, she already had a rough idea of Vincent's gift. Just like the others with gifts similar to Mystic Eyes or perhaps cultivation talents, Vincent also had one which is related to enhancement or modification techniques.
She wasn't exactly sure how it works but it seems that he can bring out the best of whatever item he was holding.
There was a time when she brought Vincent a Magic Artifact that she found inside a dungeon and it was supposedly a useless item. However, after Vincent took it with him for a while, the pendant that she found suddenly became brand new and its skills had somehow awakened.
