Michael Shurkin made an interesting response to a related question on Quora link:

Article 1, Section 8 of the US Constitution states that Congress has the following power:

"To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water;"

A letter of marque is a kind of a naval hunting license. It allows a private citizen to fight on behalf of the government in wartime, stopping and capturing enemy vessels on the high seas. This is called privateering. In order to wage war at sea the said private citizen would have to have a warship. That would be something like the frigate in the picture, a ship armed with cannon.

Since one cannot be a privateer without a warship, the fact that this is in the Constitution demonstrates that it's authors fully expected armed warships to be in private ownership. A warship was basically the WMD of it's day, the most destructive weapon in existence. A ship's battery could level a coastal city.

So, the argument that the weapons the Founders knew about were limited to muskets and swords is completely baseless. The founders might be shocked by many things in our day (women voting?), but weapons wouldn't be one of them.

If you would like to propose legislation on weapons, you may wish to actually study the subject first. Flintlocks are a type of a muzzleloader, and scabbards are not weapons at all.