Can a character take an Edge with an Advance that uses an Edge they got from a Magic Item as a pre requisite. For Example say I had a "Gum Shield of Frenzy" could I get Improved Frenzy.
I see a few options here. I'm a generous and fun-loving GM so I've sorted them in my preference.
Yes, but only when using the item. Let the character take Improved Frenzy, but they must maintain the prerequisites to use Improved Frenzy. If they stop using the shield, they lose all benefits of Improved Frenzy until they regain Frenzy (by any means.)
No, but make the edges cumulative. Let the character learn the Frenzy edge. The shield provides the benefit of Frenzy or Improved Frenzy depending on who wields it.
No, suck it up. It's a tough world. Just because you have a crutch that lets you walk doesn't mean you can use it to run.