It is good practice to inspect attic wiring especially in older homes, this was a century home that had been rewired. The sheathing on the branch wire had been damaged by vermin, possibly squirrels or mice. Any more damage to the sheathing would have exposed the copper wire which would have been a fire hazard. I recommended a qualified person inspect the attic for signs of vermin and repair any holes that would allow easy access. A licensed electrical was called to inspect and repair all attic wiring.