The only "used only for magic" language that I am aware of is Enochian, as channeled by John Dee and Edward Kelly. There are several good books on Enochian, but the one that I have found that has the best pronounciation is The Complete Enochian Dictionary by Donald C. Laycock. It presents Dee's original pronounciation guidelines.
All language has a magical quality because, when used correctly, language has the ability to effect the subconscious mind and create or modify reality. Most languages have other magical qualities, such as Hebrew, whose individual letters have magical coorelations. Japanese has "words of power" used in kotodama, and then the common words. Many more exist if you look for them.
What you might look more into is not so much a new language, but how to use the one you already have. You have the ability to put intention and energy in with every spoken word. In fact, you alreay do. You probably just don't realize it most of the time. In addition to that, taking a course in conversational hypnosis or NLP would be very beneficial.