Arbiter Lupis in Nerva, he is next to the AE building.
Also Arbiter Sawyer in Port Oaks. He's by the Pocket D entrance and Black Market and the Arena. His coordinates are (-1304.3, 144, 1295).
For those who aren't good with coordinates (since they AREN'T convenient to use), select Pocket D on your map while in Port Oakes, go to the door it selects, and walk around the side of the building to the right. He's about 1/3 of the way around the building.
@Roderick
As a rare visitor to the Rouge Isles..where does one go to get your respecs done?
"We need Cadaver cleanup in back alley 4..."