I was reading Wikipedia's "Dart" article when I came across a paragraph claiming that a sort of "fletched spear" was used in the Middle Ages and Renaissance. The only source provided are two paintings by Titian from the 1500s: Venus and Adonis, and Diana and Callisto. Here are links to hi-rez images of them.
https://upload.wikimedia.org/wikipedia/commons/e/e5/Venus_and_Adonis_by_Titian.jpg https://upload.wikimedia.org/wikipedia/commons/1/1a/TitianDianaCallistoEdinburgh.jpg
In both you can see individuals holding the shafts of what look like very thick, nockless arrows. The most prominent one is held in Adonis's right hand. Based on my own hand, the shaft appears to be 1.25-1.5 inches in diameter, the thickness of a typical martial spear haft or quarterstaff. Far thicker than an atlatl dart and suggesting this type of spear could be used for hand-held stabbing in addition to throwing. If the one held by Adonis is assumed to be resting with its tip on the ground (unseen), it is over 6 feet long. The fletchings are plainly visible and look like scaled up versions of those used on arrows.
However, two paintings by an artist depicting ancient Roman legendary figures seems like a spotty source to claim this weapon existed. Is there any other evidence for such a type of spear during this time period?
While no one answered my question, I was able to unearth more information in the subsequent days. I will now answer my own question on this thread for the benefit of other curious people who may find this thread later, since google results include reddit threads.
It would appear from multiple sources that Medieval and Renaissance Europeans did indeed use "feathered spears" such as those shown in the paintings above. They are referred to by most sources as "darts" since they have both fletchings (which distinguishes them from javelins) and are not launched by a mechanical device (i.e. arrows, bolts, or quarrels). Sources seem to suggest they were both used ceremonially and as true martial weapons.
The most comprehensive source I found is "Hafted Weapons in Medieval and Renaissance Europe: The Evolution of European Staff Weapons between 1200 and 1650" by John Waldman, published in 2005. A pricey text, but in my opinion, one of the best modern texts on medieval weaponry I have ever come across. Waldman discusses these "darts" one page 81-83, with pictures attesting to the weapon on page 148 and the first colour plate of the book.
Waldman suggests there may be no surviving specimens of these weapons since they are fragile in nature. I also infer based on my own understanding that if a specimen did survive, the fletchings might have rotted away before the shaft and point, leaving what for all the world looks like a normal spear. Another possibility that occurs to me is they may have been mis-cataloged as siege weapon bolts, such as an arbalest (aka siege crossbow). However, they are depicted in quite a number of illustrations and artwork being held or used.
Waldman lead me to multiple other sources, including the article "Ceremonial Arrowheads from Bohemia" (Nickel, Helmut; Metropolitan Museum Journal, v. 1, 1968) which can be found here for free: https://www.metmuseum.org/art/metpublications/ceremonial_arrowheads_from_bohemia_the_metropolitan_museum_journal_v_1_1968#
Nickel, a much older work, seems to operate under the assumption that all these darts are simply "giant arrows" that serve purely as ceremonial or symbolic items. This can be seen in several works of art from around 1515 where the dart is held by Emperor Maximilian I as though it were a scepter as he holds court. It is similarly depicted in this way in an anonymous wood cut found in the 1485 text of "Le Chevalier délibéré" where a ruler seated on the throne holds what looks like a very large arrow.
However, there are other illustrations showing them wielded in battle as a throwing and stabbing weapon. The St. Lambert panel from 1430 depicts King Ludwig of Hungary fighting the Turks; in it, an armored soldier can be clearly seen at the top holding a ~4 foot long dart with fletchings and a barbed point, about to stab an opponent he is holding back with his off-hand. The Clovis Tapestry in Rheims depicts a mounted soldier holding a similar weapon overhand as though about to throw it. The aforementioned "Le Chevalier Délibéré" (1485) that contained the ceremonial depiction also shows a sort of judicial battle where an armored man prepares to throw a dart at his opponent, while "Death" officiates in the background, holding a similar dart in a ceremonial manner. Two later pieces by Albrecht Dürer also show a 6-7' fletched dart held by a Landsknecht officer, as well as one wielded in a confrontation between armed men where it is shown held overhand as though about to stab or be thrown.
The two paintings by Titian originally mentioned above are also curious in that the points of the darts are not visible, which implies the viewer should recognize what they are. This cases doubt on the idea of them being fanciful depictions of something non-existent.
It is interesting to note that the depictions show the darts as having a thick shaft, roughly equal to other pole weapons seen in the works, compared to a javelin that would likely have been thinner. This might support the idea of dual use for both stabbing and throwing. However, they also tend to depict the point as having barbs like a broadhead arrow, which would make them impractical as a striking weapon (they would become stuck in the enemy and difficult to withdraw).
