Legendary Weapons
 

If my memory serves me right there are only two famed weapons Lost Sword and Mercers Blades correct?

The only two legendary weapons are the once you just said, but there are several Famed weapons.

So far, that is. There's a huge possibility that we'll see more legendary weapons in the future, such as a regular dagger, pistol, doll, blunder buss, staff, etc...

Yes, that is true... unless there is some Dagger form of Mercer's Blades, but I doubt it...