What is the ruling on saying "So-and-so knows no fear" to express courage, and can it be understood to mean that he does not fear Allah, thus constituting disbelief (kufr)?

Such phrases do not signify fear of Allah Almighty and His punishment; rather, they express courage by negating fear of created beings. Therefore, there is no disbelief in them. They fall under the category of a general statement intended to convey a specific meaning, or an absolute statement intended to convey a restricted meaning, like when someone says: "So-and-so does not know love," meaning a specific kind of love, not the love of Allah, His angels, and His messengers. An example of this is the statement of Salama ibn al-Akwa': "Do you not honor a noble person nor revere an honorable one?" He replied: "No, unless it be the Messenger of Allah, peace and blessings be upon him." Thus, Allah Almighty is not encompassed by this phrase.