Weber, known as "Mr 20%" since brokering Schumacher's huge Ferrari contracts, is worried that Red Bull ace Vettel's personality might not be so suited to the task when he joins Ferrari in 2015.
Ferrari is expected to announce Vettel's arrival as departing Fernando Alonso's replacement ahead of the 2014 US F1 GP on November 2.
'LOT OF POLITICS'
Famously, in 1996, his countryman Schumacher similarly arrived at Maranello as the reigning champion and within five years Ferrari was established as F1's dominant force.
Weber told Germany's Auto Bild: "Sebastian is much more sensitive than Michael. If something is not working well, the pressure at Ferrari is greater than it is anywhere else. It's not always 'peace, joy and pancakes' but a lot of politics. I think if a Fernando Alonso could not deal with it, then nobody can."
Red Bull's Helmut Marko, who groomed Vettel but is now losing the 27-year-old to his arch-rival, also doubts Vettel can match Schumacher's feats. Schumacher benefited in his time from an unlimited number of test kilometres and close co-operation with tyre partner Bridgestone, about which Marko commented: "They are advantages that no longer exist."
PROJECT '666'
Also doubting Vettel's ability to match even Alonso's feats at Ferrari team is former F1 driver Robert Kubica, who was close to Alonso: "I think Vettel is not so strong as Fernando. Even without a great car, Fernando won races."
The latest whispers from Maranello are also not positive. Italy's Autosprint claims Ferrari engineers were unhappy with the first set of aerodynamic figures after wind-tunnel testing the 2015 car, whose project is, bizarrely, codenamed '666'.
The 2015 car will be the first Ferrari to be produced under the technical leadership of James Allison.
Stay with Wheels24 for the 2014 F1 season – fresh reports every day.