Is it Gem of a Soul by spuffyluvr?
In this fic Spike has the gem of amarra and kidnaps buffy. He takes her on a road trip to 'give' to dru.
I remember that he went to LA to taunt Angel about having Buffy. He eventually kidnaps Angel and keeps both him and Buffy in the same room. Buffy is tied up on the bed while Angel is chained to the wall. He says he doesnt want to rape Buffy because it will hurt Angel more if she enjoys it.
Not sure about the sword, though.
Oops. Missed the msg about Spike being the overlord. Sorry
