In total, these details are as follows: 1) The broom animates when enchanted, 2) The sunlight grows dim, 3) The broom emits light and particles, and 4) a sound effect plays (although you can't hear it in the screenshot below). In the case of the levitation spell, the broom rises slowly off the ground to the specified height and begins to pulse up and down.
One critical thing we're missing is that the character doesn't animate during the act of spell casting. This is a big deal. Even from the video below, it's clear that the broom has been enchanted, but not that the character cast a spell. So my next goal is to model our main character and the associated animations (running, walking, idling, jumping, and spell casting).