Final answer:
In the Harry Potter series, Harry gives Arthur Weasley a penknife as a Christmas present in St. Mungo's.
Step-by-step explanation:
In the Harry Potter series, Harry gives Arthur Weasley a penknife as a Christmas present when he visits him in St. Mungo's Hospital during the Christmas holidays.
The penknife is a thoughtful gift as it reflects Arthur's fascination with Muggle objects and technology, and it demonstrates Harry's knowledge and understanding of Arthur's interests.
Overall, the penknife is a symbol of the friendship and camaraderie between Harry and Arthur.