I’m going to take a wild guess and say that Vulture’s “fantastic power” is flight.
Amazing Spider-Man (Vol. 1) #2
Published: c. March, 1963?
Cover Date: May, 1963
“Duel to the Death with the Vulture!”
Writer: Stan Lee
Artist: Steve Ditko
Inker: Steve Ditko
Letterer: John Duffy
@hornacek — In this panel, Spider-man already has the Vulture’s ankle and is wound back to throw a punch. I give Adrian about half a second.
“I’m going to take a wild guess and say that Vulture’s ‘fantastic power’ is flight.”
I think it wasn’t until the Vulture story in Roger Stern’s ASM run that it was established that his harness gave him super-strength, agility, etc. Up until then he was just a normal guy with wings. I don’t think in any of the Lee/Ditko/Romita stories it said that his punches were super-strong, which means in all of their fights Spidey is being punched by a normal senior citizen.
A simpler time for Spidey. I wish I was alive to see this comic on the rack when it was new.