Fox News reported in its Entertainment newsletter that Harry risks "lobbing a grenade" at William, according to the headline of an item in the publication. The headline is the only description of that claim in the source material, and the source does not say what form such a move would take.
According to Fox News, the same newsletter headline also reports that Kate brings back Diana's tiara. The source does not describe the occasion, the location, or any other detail of that report.
The item appears in the Fox News Entertainment newsletter, which Fox News describes in its summary as a guide to "the latest Hollywood headlines." The summary is general and does not refer to either item by name.
The source lists no author for the item, so it does not identify who wrote the newsletter entry. The two matters appear together under one headline, and the material provided contains no quotes from any person involved, no official statement, and no response from the people named.
Fox News has not been shown to have reported further detail on either item in the material provided, and this account relies only on the headline and the summary. Coverage by other outlets was not part of the source material. A reader seeking more would need the full newsletter item, which is not reproduced in the material provided.