why am i not having any famed weapon luck?

[Cannon Leader]

I wish there was a fool proof way to get famed weapons. I hadn't gotten a single famed weapon until I was level 36, and then suddenly I picked up 3 famed weapons in the span of one hour - Shaman Doll from Darkhart, and Corsair's Cutlass and Master Fencer's Sabre from Brinescum on the bridge at Tormenta. I would say it's random, but I find it odd that once I got the first famed weapon, I found myself getting skull chests much more frequently now. Not sure if that has to do with using higher level weapons, but it is an interesting coincidence.