Final answer:
Henry Clay and John C. Calhoun were angered over the British scalping knife because it symbolized British support for Native American resistance against the United States.
Step-by-step explanation:
Henry Clay and John C. Calhoun were angered over the British scalping knife because it symbolized British support for Native American resistance against the United States. The British were providing Native Americans with military weapons, including the scalping knife, to fight against American settlers. Clay and Calhoun saw this as an insult to American honor and a threat to the country's westward expansion.