Is the Feather Touch No.7 cosidered a big nib ?
Is it a rare nib ?
Was there a bigger nib produced at the time by Sheaffer ?

It's on the larger side, but it's not huge by any means. It's not rare; perhaps hard-to-find, but not rare. Sheaffer made larger nibs during the same period, including the 8-sized Lifetime and Feathertouch nibs.

Why do you ask?

--Daniel