This is true... Jim never designed a knife. The knife Jim used in the sandbar fight was simply "Jim Bowie's knife".
At that point in history, "The Bowie Knife" did not exist. "Jim Bowie's knife" did exist. The knife in question (Jim Bowie's knife) was designed by his brother, Rezin Bowie. So essentially, "Jim Bowie's knife" was an 1820s "custom knife" made to the designer's specifications by the designer.
Now the question is "Who made Jim Bowie's knife?" Two real possibilities exist - Either Rezin, himself, or the Bowie Plantation blacksmith of 1826/27 - Jesse Clift.
As published in Rezin's own letter to The Planter's Advocate dated August 24, 1838.
"The first Bowie knife was made by myself in the parish of Avoyelles, in this state (Louisiana), as a hunting knife, for which purpose, exclusively, it was used for many years."
However, according to Rezin's granddaughter, she said that her mother told her she (Rezin's daughter) had watch their blacksmith, Mr. Clift, make the knife under Rezin's supervision from an old file.
And what were Rezin's specifications?
In the same 1838 letter, Rezin described the knife specifications as being...
"The length of the blade was nine and one-quarters inches, its width one and one-half inches, single edged and not curved..." like a large butcher knife. Later it was said that the knife has a SMALL guard, as (depending on the story) either Jim or Rezin had cut themselves cleaning a rabbit when "his" bloody hand slipped.
Rezin was quoted as saying that the knife he made did not look like the "Bowie knives" of the time, but that he thought that Jim would have liked what they had evolved into.
So the bottom line is that "Jim Bowie's knife" was a hunting knife, similar in size to a large butcher knife, not a "fighting" knife.
Anything made after 1827 are "knife makers' fantasy knives" made to fit their own visions of what kind of knife they would have used in such a fight as "The Sandbar Fight" or rather, what they (the knife makers) thought the American public of the 1830s and later wanted in such a knife.
Kind a like what knife makers do now-a-days.

Take an idea and try to make money out of it.

