I can't answer on the WiK mini, but I would assume that if their price stayed stable then it means they most likely still drop.
For the Raven Staves they drop in the desert (got one my self in a chest near the minotaur in Elona Brief) and they also drop in the Jungle (a guy I know got one while VQing a zone).
Not sure of their correlation to dropping SOTW or Aegis, these are core skins so they can drop in many places.
I don't think that Raven and Aegis/SotW share the exact same drop pattern but they have some similarities for sure.
Aegis/SotW are core skin but they seems limited to mid/high level foes. They don't drop in Ascalon (or at least don't drop on the Nolami charrs that have been abundantly farmed), as far as I know they don't drop in the Nothern shiverpeak and all the people I have asked haven't been able to confirm they drop in Shing Jea either.
They seems to drop in the maguuma jungle (a wiki entry mention a drop on a behemoth in the Fall) but I haven't been able to get one after a lot of chest running and troll farming in Reedbog, so I would assume they are rare (as rare as the Raven ?)
They seems to have the usual drop rate on all the other area, Faction main island, Krytia, Crystal Desert, Southern Shiverpeak and Ring of fire.
Side note on the raven :
Display Spoiler

How do we explain this prenerf one ?