Bruce has never really... understood, magic. Or, well, perhaps that's not true. He's encountered magic, certainly. He's seen it work, he understands it conceptually. He can certainly posit theories about the machinations involved, the flow of energies, the bending of physics, the natural laws that must still apply even when they appear to be breaking. 'Magic is just science we don't understand yet', or something to that effect. Sure, in that sense, he gets it.
Perhaps it's more accurate to say he doesn't like magic very much. He's a man of logic, science, technology. And in truth, while he certainly has encountered magic in his work as the Dark Knight, it's somehow more of a... Metropolis, issue? Gotham sees much more runaway science than anything that could truly be called magic, after all. Even if what, say, Poison Ivy can do may certainly appear magical, he knows there is a scientific basis, and moreover a scientific explanation, behind her abilities. ...Maybe that just backs up the aforementioned theory, granted.
Whatever the case, he wasn't exactly... prepared, for the newest member of the Family to begin showing an aptitude for magic. Truthfully, he hadn't even known what he was seeing at first. But the more things happened, the more it became clear you had ability - talent, even. Things he doesn't understand - but things that are effecting your life, and will continue to do so. And that means it's something he can't ignore.
On a practical level, he can acknowledge that having a magic-user on the team could be beneficial. On a personal level, it doesn't matter what he feels about magic, because you're a member of his family. What is important to you is important to him. So, he might not like magic, or get it, but... he's trying, right?
"Okay. So... show me that again." Bruce crosses his arms and frowns thoughtfully. He was still insisting on your physical training, of course. But now, integrating your growing magical skill was also part of your training.