I read this decades ago—probably in the 1960s—and am pretty sure it was from an anthology. It was English language. As a boy, our hero had nightmares, and his father taught him how to mentally bring something into his dream to protect him. I think his father might have been a police officer, so the item was his gun, which had a nickname. The trick worked. Then, as an adult, the man runs into something supernatural or occult, perhaps a curse used against him, and the curse or entity invades his dream. He remembers to call on his father's gun, which grows to enormous proportions in the dreams and offs the bad guy.
Having used lucid dreaming myself I have always remembered the story. I used it as a plot device in a short story, and I would like to give credit to the inspiration.