[CapedCrusader]

Hiya, Street, been away for a bit.

"The setting includes a total of 21 Powers available at a various Ranks. ... When the AB(F) Edge is taken the player gets two specific Powers, ... Additional Powers can be acquired by taking the New Power Edge."

How about this? The idea of using Edges is a good one, I think. Create Fringeworthy as an Edge. There's no need to actually make it an Arcane Background or even call it one, just call it Fringeworthy as a Background Edge.

If they get two specific abilities when taking Fringeworthy, just add those abilities to Fringeworthy. If you want to create them as Edges, go ahead, just attach eval script code so they don't cost Edge points and bootstrap them to Fringeworthy. This has the advantage of listing them separately with the other 19.

For the other 19, rather than creating a New Power Edge and the AB baggage that goes with it, just create them as regular Edges under the Power Edges type. That way they cost Edges to buy like the New Power Edge would have. Also, you don't have to worry about any of the Arcane Background widgets that (from the sound of things) Fringeworthy doesn't need anyway.