How can a student of knowledge be brave, standing up for truth, and not fearing blame in Allāh’s path?

This (bravery) is a gift bestowed by Allāh to whomever He wills. No one can learn bravery, it is bestowed. The coward (remains) a coward, even if you gave him all of the weapons, he does not feel responsible in front of Allāh (تبارك وتعالى) and that Allāh (تبارك وتعالى) has tasked the believers with enjoining the good and forbidding the evil, and that they call to Allāh (تبارك وتعالى): “And let there be (arising) from you a nation inviting to (all that is) good.” (3:104-). Meaning, they call to knowledge and teaching, “and enjoining what is right and forbidding what is wrong.” (3:104-).

This is a definitive affair, so let him feel responsible in front of Allāh (تبارك وتعالى). This affair is obligatory upon the whole ummah, when some of them establish it, the blame is removed from the rest. It is like all of the collective obligations, when he who suffices establishes it, there could be one person who embarks upon knowledge and spreads knowledge, and by his side are others, vacant (idle), dead. They do not fulfil the requested obligation, so they must stand by the side of this one and that one in raising the flag of Sunnah and Tawḥīd, and reviving the ummah from its decline.