I think the OP is overthinking things. It's a word that isn't even being used in reference of what the OP is thinking it is referencing. The name, as it is now, is perfectly fine. People even mentioned the lore behind it as to why they're called slave. Read it, OP. Then you'll understand more.
Jumping to conclusions and making assumptions without looking into the context is a rather closed-minded thing to be doing.
The thing is, this is coming back up again because they DID change the names with this new patch. Slave weapons are now Raven weapons.