Where is the best place to find famed and legendary weapons?

[Crimson Rose]

I picked up another famed blade in Isla Tormenta today. It was in the large cavern with the spineskulls and flotsams that is separated down the middle with a stream with a granite bridge across it. I killed off a spineskull and just noticed the unexpected item in the skull loot chest. I'd been there for a while because I was doing "live" practice with my grenades. I was surprised because I got the impression that these things were mainly found in the treasure chamber.

What am I supposed to do with all these blades? I can only use one at a time after all. Why can't I give them away to other pirates?

Crimson Rose