Final answer:
The problem with William becoming a knight is that it goes against the reserved status of knighthood for the nobility, and if caught, he could face severe punishment ranging from fines to execution for fraud or treason.
Step-by-step explanation:
The problem with William aspiring to become a knight lies in his social status. Knighthood was traditionally reserved for individuals of noble birth, and a man like William, presumably of lower status, would be committing a severe transgression by claiming the title and honors of knighthood without entitlement. If William were caught impersonating a knight, the consequences could be grave, potentially leading to charges of fraud or even treason, resulting in punishment that could range from financial penalties to imprisonment or, in extreme cases, execution.
These historical customs and the severe repercussions associated with violating them were meant to preserve the social hierarchy and the privileges associated with the nobility and chivalry. Misrepresentation of one's social position was seen as an affront to the established order, and thus the penalties were correspondingly harsh to deter such actions and maintain social and legal order.