Mmmh, if in your tradition there are only angel, djinn, and human, then fae, elf, vampire, etc are djinn. However, don't forget that other traditions have different perspectives. E.g., a black pig entity may as well be wereboar or boar shifter.
A black pig wearing underwear reminds me of that Black Mirror episode though : p
If you wish for spell of courage, I agree with others that you need strong protection. The more you know that you are protected, the less insecure you are. For that, there are verses from Quran famous for it, as well as specific Arabic prayers.
Another point is that you need to understand and accept the risk and consequence of what you're trying to do. E.g. you said someone lost their ability to speak due to djinn. Then assuming your protection fails when dealing with this entity, you need to accept that you won't be able to speak anymore until someone successfully cures you. If you can accept this risk, then why are you still afraid?
By the way, which book are you trying to translate?
"Knowing a trifle about everything gives life more color." - Zhuge Liang
"Always and never are two words you should always remember never to use." - Wendell Johnson
"May you live in interesting times, may you be recognized by people in high places, may you find what you’re looking for."