Unfortunately, you have mentioned something that does not exist - <<... story about a family crest with a gauntlet and a flaming sword on it. >>
There isn't such a thing as a 'family crest'. Perhaps the conveyor of the information wasn't aware of this fact.
If the originator of the information really meant to say, "... story about a family shield (or Coat of Arms) with a gauntlet and a flaming sword on it", that's another matter entirely.
To me this is what the person meant to say when they referred to it as being 'on it' - they were describing a shield and not a crest.
Without any tinctures (heraldic colours, metals, furs, stains) mentioned it would be very hard to nail this one down. Do you have any further info that might help us?
To what were you referring when you said, "...but the current FLEMING crest " - what is meant by 'current' and 'Fleming crest'.