Well, you really couldn’t have come to a better unicorn. I could tell you just about everything here is to know about magic, how it works, how unicorns use it, how other creatures use it. I likely know things that even somepony like Twilight Sparkle probably wouldn’t be trusted with, considering her potential and the dangers involved at this stage.

I couldn’t teach you a spell, but I could probably answer every question you could ever think of about magic theory. But I can’t.

Exactly how magic works isn’t meant for everypony to know. It holds certain risks from outside parties and even other unicorns. It’s a closely guarded secret and only a few ponies not connected to the royal family are permitted to know certain bits and pieces to preform their jobs. The only reason I know is that I stumbled upon some things back when I lived in Canterlot and asked some questions. I was trusted by the royal family and given the knowledge because there isn’t really anything I can do with it; I’m too magically frail.

About your specific question, this is what I can tell you. There is no way for an earth or pegasus pony to use magic like a unicorn. They can use objects with minor enchantments like wards or protections, but that’s it. If you want to study a magical substitute, I’ve recently learned of how powerful potion brewing can be. But the applications will be different.

That would be the royal family’s answer, so that’s all I can say about it.