A bodkin point is a type of arrowhead. In its simplest form it is an uncomplicated squared metal spike, and was used extensively during the Middle Ages. The typical bodkin was a square-section arrowhead, generally up to 4½" (11.5cm) long and ⅜" (1 cm) thick at its widest point, tapered down behind this initial "punch" shape. Bodkin arrows complemented traditional broadhead arrows, which continued to be used, as the sharp, wide cutting surface of the broadhead caused more serious wounds and tissue damage than the bodkin arrowhead.
The name comes from the Old English word bodkin or bodekin, a type of sharp, pointed dagger. Arrows of the long bodkin type were used by the Vikings and were continued to be used through the Middle Ages. The bodkin point eventually fell out of use during the 16th and 17th centuries. Firearms were beginning to dominate the battlefield and would make infantry armour largely obsolete in the coming centuries, though it was still used to a limited extent as late as the First World War.
Armour penetration 
It has been suggested that the bodkin came into its own as a means of penetrating armour, but research by the Royal Armouries has found no hardened bodkin points, though only two bodkin points were actually tested, not a statistically relevant number. Bodkins did, however, have greater ability to pierce mail armour than broadheads, and historical accounts do speak of bodkin arrows shot from close range piercing plate armour. Broadheads were made from steel, sometimes with hardened edges, but were more often used against lightly armoured men or horses than against an armoured adversary.
In a modern test, a direct hit from a steel bodkin point penetrated Damascus chain armour, although at point blank range. However, the test was conducted without a padded jack or gambeson, which was layered cloth armour worn over heavier armour for protection against projectiles, as it was known to stop even heavy arrows. 
Armour of the Medieval eras was not completely proof against arrows until the specialised armour of the Italian city-state mercenary companies. Archery was thought not to be effective against plate armour in the Battle of Neville's Cross (1346), the siege of Bergerac (1345), and the Battle of Poitiers (1356); such armour became available to European knights of fairly modest means by the late 14th century, though never to all soldiers in any army.
Some recent tests have demonstrated that needle bodkins could penetrate all but heavy steel plate armour; one test used padded "jack" armour, coat of plates, iron and steel mail and steel plate. A needle bodkin penetrated every type, but may not have been able to inflict a lethal injury behind plate.
- Royal Armouries: 6. Armour-piercing arrowheads
- Hunting with the Bow and Arrow, by Saxton Pope. http://www.gutenberg.org/dirs/etext05/8hbow10.txt "To test a steel bodkin pointed arrow such as was used at the battle of Cressy, I borrowed a shirt of chain armour from the Museum, a beautiful specimen made in Damascus in the 15th Century. It weighed twenty-five pounds and was in perfect condition. One of the attendants in the Museum offered to put it on and allow me to shoot at him. Fortunately, I declined his proffered services and put it on a wooden box, padded with burlap to represent clothing. Indoors at a distance of seven yards, I discharged an arrow at it with such force that sparks flew from the links of steel as from a forge. The bodkin point and shaft went through the thickest portion of the back, penetrated an inch of wood and bulged out the opposite side of the armour shirt. The attendant turned a pale green. An arrow of this type can be shot about two hundred yards, and would be deadly up to the full limit of its flight."
- Embleton, Gerry & Howe, John: "Söldnerleben im Mittelalter", p.47, Motorbuchverlag 1994
- "Medieval Military Surgery", Medieval History Magazine, Vol 1 issue 4, December 2003
- Strickland M, Hardy R. The Great Warbow. Sutton Publishing 2005. Pages 272–278: "even at a range of 240 yards heavy war arrows shot from bows of poundages in the mid- to upper range possessed by the Mary Rose bows would have been capable of killing or severely wounding men equipped with armour of wrought iron. Higher-quality armour of steel would have given considerably greater protection, which accords well with the experience of Oxford's men against the elite French vanguard at Poitiers in 1356, and des Ursin's statement that the French knights of the first ranks at Agincourt, which included some of the most important (and thus best-equipped) nobles, remained comparatively unhurt by the English arrows."