Ooh, I should come her more often, this conversation is interesting
@AAAndrew !
I'm not sure I can add anything to what you've both said already, though.
The French texts sometimes use the term oblique which is one of the appropriate words to describe this in French, so I never really paid attention to it. It just never occured to me that "oblique" might not have been the first word that comes to mind in English to describe this kind of cut...
As I said, some French masters use the word but it's not systematic. Most of them just describe the cut as being done in a diagonal or slant, or just specify that one tine should be longer than the other.
in 1680, Alais de Beaulieu (who was one of the famous copybook authors), calls one of the positions "oblique", he doesn't say much about the cut itself. The pen-holds he cites are "à face" (pen slit is perpendicular to the line), "oblique" (pen slit is at an angle), "de travers" (pen slit is almost hoizontal to the line) and "inverse" (what we'd call today the off-hand pen hold). But he prefers using "oblique" to get the same effects as "inverse"... I think he just means it's more comfortable and gives the same thick-thin potential.
Royllet in 1737 uses the word "obliquité" (obliquity ?) to describe the cut. (Démonstration de l'art d'écrire, 1737)
In 1763, Paillasson uses the word "oblique" to describe the nib cut but, as
@Estefa said, it's not very precise. The word oblique just means "slanted" in this case.
The British Masters at the time were more inclined to criticizing one another than to writing stuff that would have successfully helped people learn on their own... Those who describe the tip of the pen just say that some scripts necessitate a tip "with the part which lies next to the Hand (the writing itself) when you write, be small matter the shortest and narrowest." An illustration in George Shelley's second part of Natural writing makes this description a bit less "obscure".
None of them use "oblique" to describe this cut, some call it the French cut.
By 1730, all the books that describe the cut of the pen advise the use of a square cut for Round Hand. Bickham writes that he still uses an oblique cut for running hand and mixt secretary (the left side of the knib be rather shorter than the other). Other hands also call for other kinds of obliqueness described in the same manner. (The Surrey and Southwark writing-master... , c.1750)
After this, I only see masters who reccommend the use of square nibs, or finer points.
Of course, this is only for quills... All the masters seem to agree that cutting a pen is more an art than a science, every penman will have a cut that fits his own position or style.
I don't have any information regarding steel nibs themselves. I guess you could have more information by asking a collector. Looking at Kallipos.de "left-handed" nibs section, I don't see a lot of French manufactured nibs, or mentions of the word "oblique".