This phrase has been used to lampoon movie heroes for a long time, most notably in Monty Python and the Holy Grail.
Was it ever used in a serious way in some movie? I figured this all must have started somewhere.
Don’t know about movies. I heard it in everyday life and I think in books well before MP&tHG
Heck, I’m sure there are innumerable war movies, westerns, and even cop shows that used the phrase sincerely before and after 1975.
I am pretty sure Monty Python is the source of the quote. I am sure someone somewhere else said it before them but when people make the reference, they are referencing MP.
I like the way it was put in The Magnificent Seven best:
“You elected?”
“No. Got nominated real good.”
I don’t know if any of the Three Musketeers actually used the pharse, but they resumed action after getting wounded enough times to justify the line.
Oh yeah. Books. 
Well, I doubt the clip I linked was the first time this was used as satire. I was just wondering if there was a single movie (or book) that used this phrase in such a way as to inspire satire. OTOH maybe it was such a common phrase that it was satirized because of its overuse.
Not at all. One heard this often in TV and movie westerns in the 50’s and 60’s. Monty Python is quoting THEM. Seriously.
Booth Tarkington uses it, or rather, Penrod does when he writes his detective novel in 1914:
“It was just a fletch woond and would heel soon.”
Which would imply that Penrod heard it rather than read it I suppose.
Fearless Fosdick would often suffer major injuries that he would shrug off as only a flesh wound. He existed in the L’il Abner strip, that ran from 1934 to 1977.
Not what the OP was asking, but the line is used by Jeff Dunham’s Achmed the Dead Terrorist