Fixes nonfunctional pistol bayonet and adds sword bayonet.

Note: it still doesn't properly update the gun's inventory display to show the added damage because I don't know how to do that. It does however fix the pistol bayonet so that the bonus damage is actually applied.

On the sword bayonet:

A sword bayonet is any long, knife-bladed bayonet designed for mounting on a musket or rifle. Its use is thought to have begun in the 18th century and to have reached its height of popularity throughout the 19th and into the early 20th centuries. When unmounted from a musket or rifle, sword bayonets with their typical hilts and long blades also could be wielded as short swords. While modern military bayonets typically have knife blades, they are usually too short to be called sword bayonets and are more akin to fighting/utility knives. Japanese Type 30 bayonet (made between 1894 and 1945), an example of a straight-edged sword bayonet.

Sword bayonets originated for use with muzzle loading rifles. A typical example of an early sword bayonet is the 58 centimetre (23 inch) blade variety designed for the Infantry rifle, later called the Baker rifle of the Napoleonic era British Army.

---  From Wikipedia