I don't know if he faked it, he could have gotten what you would call in American football a "stinger".
The injury usually involves nerves traveling from the spinal cord to the arm, but sometimes involves nerves in the neck. This happens in one of two ways: either the head and neck are forced toward the shoulder, compressing the nerves that lead from the spinal cord to that arm, or the head and neck are forced away from the shoulder, stretching those nerves. It is for this reason that stingers do not affect both arms simultaneously, however it is possible for both arms to accrue injuries. Symptoms often disappear within minutes and usually within hours, however, repeated nerve trauma can cause recurring stingers, chronic pain, and muscle weakness.
I believe I saw both Rich Attonito get one from Jake Hecht and maybe Abel Trujillo on Marcus LeVesseur.