The legality of asking such a question largely depends on the context and location. Here are a few examples:
Law enforcement: A police officer or other law enforcement official may have the right to ask if you have a weapon on your person, especially if there's a reasonable suspicion that you might be involved in criminal activity. This varies by jurisdiction and is subject to local laws and regulations.
Private establishments: Owners or managers of private establishments (like bars, clubs, or some businesses) may have the right to ask you if you're carrying a weapon, as they often have rules against bringing weapons onto the premises.
Airports or other secure facilities: Officials at airports or other secure facilities will definitely ask about weapons as it's part of their security protocol.
Personal interaction: In a general personal interaction, asking someone if they have a weapon on them can be considered quite invasive. It might not be illegal, but it could be seen as an invasion of privacy or even threatening, depending on the context.
In general, how you answer is up to you. If you're not in a situation where you're legally obligated to answer and you feel uncomfortable with the question, you have the right to decline to answer. However, lying to law enforcement officials can lead to criminal charges in many jurisdictions.
This is a generalized response, and the laws and rights pertaining to such interactions can vary greatly by country, state, or even local jurisdictions. It's always best to seek advice from a legal professional for accurate information.