I have a theory :
Darkbanes are corupted Shadow clans warior
Darkbanes are corupted Shadow clans warior
Interesting, but if we look at it from the example of Minecraft (HERE ME OUT) it could be possible they are like realm exclusive counterparts. Shadow Clan are like Endermen, they appear in the Caverns (I guess the End since we got the Surface?) (and if theres a Shadow Realm then they go there too) whilst Darkbane are like Wither Skeletons, exclusive to the Deep Caverns (aka Nether).
Yeah ,that's possible