(This doesn't have terms that are often described in other guidebooks or if they don't have a different meaning in this one)

Sigma: This is a term for lone wolves. 

"Sharpen(ing) their Claws": This has multiple meanings. One could mean someone is getting ready to protect something or someone. Another is that someone is super aggressive.

Heat: The way that you can tell if one is going into heat is more accurate to how you can tell if your pet dog is going into heat. There's also other random signs as well. Ex. Chewing on their own arm, becoming lazy/lazier, being more productive, but it all really depends.