The manufacture of a spear in the Middle Ages would've required much less valuable materials than to produce alternative weapons of the age, such as swords. Shafts would've been made of light ash wood, cut from a coppice, and the spearheads would've been produced from a relatively small quantity of valuable iron (in comparison to the huge quantities required for the forging of a sword).
Thrusting Spears
The morphology of thrusting spears varies widely, but they were generally fairly narrow, flat, and leaf-shaped, with sizes of spearhead normally ranging from 6 to 13 inches. A notable exception, less common than the conventional Spere may have been called the Ord (meaning "point"). This design featured a long slender head with square cross-section, about 15 inches long, tapering to a needle-like point, resembling a large version of the medieval bodkin arrowhead, and may have been designed for piercing armour.
The thrusting spear has numerous advantages over other weapons of the age, chiefly that it keeps the enemy at a distance thus protecting the warrior wielding it from slashing or bludgeoning blows from shorter range weapons. This would have been a crucial defence for the average warrior, who through most of the middle ages would be very lucky to have any armour to rely on at all.
The spear is the natural companion of the shield, which functions to protect the warrior from hand-to-hand blows by any enemy that manages to get past the spear's point. The principle battle-strategy of the age; the shield wall, relied on many spears pointed at the enemy line as the main means of attack. In later battles after the emergence of formidable cavalry use by Norman knights, such spears, possibly with shaft-ends jammed into the ground, provided the only effective defence against a charge by mounted warriors.
Without a shield, however, a spear is less effective. It is believed that many warriors would enter battle with a backup weapon, be it a seax, axe or (for the very wealthy) a sword, to allow the warrior to fend off attacks from opponents who had passed the spear-point. Experiments have shown that in individual combat, spears are less effective than swords, particularly after shield-loss.
Later in the period, the winged spear emerged, with iron protrusions either side beneath the spearhead. These were likely developed to give an advantage in spear-to-spear fencing, or to prevent the spear penetrating so deep into an enemy that it became difficult for the wielder to extract.
Javellins
Whilst, feasibly, any thrusting spear can be thrown (though often not far) they tend to not be especially aerodynamic, and are easy to deflect with a standard Saxon shield. Furthermore, throwing a warrior's main means of both defence and attack makes him vulnerable. In addition, there's always the risk that an enemy could throw it back. The arsenal of Germanic warriors in the middle-ages included purpose-made throwing spears, or javelins. Typically a warrior would enter battle with one or two light throwing spears (darod) in addition to his main thrusting spear.
The loss of a shield greatly weakens an individual opponent's sheild-wall, and weaken an enemy force by fragmenting a shield-wall. In addition, as has been discussed, the loss of a shield reduces the effectiveness of a spear-wielder. For this reason, the disabling of enemy shields was a major objective of any army. The most note-worthy example of Anglo-Saxon javelins; the "Angon" was probably the namesake of the Angles and the English, and was purpose-made to embed into enemy shields and be impossible to remove, effectively and permanently disabling the shield and possibly maiming the warrior holding it. Designed with a long slender shaft meeting a short wooden section, reminiscent of and likely descended from the Roman "pilum". Sharp barbs close to the point would make extracting it from the wood of the shield (or the body of an unlucky victim) extremely difficult.
The 6th century commentator Agathius describes the use of the Angon in great detail;
"If the angon hits an enemy, the spear is caught in the man and neither the wounded man nor anyone else can draw it out. The barbs hold inside the flesh...
If the angon strikes a shield, it is fixed there, hanging down with the butt on the ground. The angon cannot be pulled out because of the barbs... nor can it be cut off because the shaft is covered with iron. When the frank sees the situation he quickly puts his foot on the butt of the spear, pulling down and the shield holding it falls leaving the head and neck unprotected. The unprotected warrior is then killed either with a stroke of the axe, or a thrust with another spear."Besides weapons of war, it is likely that less sophisticated javelins may have been used day to day for hunting, alongside thrusting spears that may have served a dual purpose as both battle weapon and hunting tool.
Swanton, M.J. (1973). The Spearheads of the Anglo-Saxon Settlement. London: Royal Archaeological Institute.
Martin, Paul (1968). London: Herbert Jenkins. p. 226.
Underwood, Richard (1999). Anglo-Saxon Weapons and Warfare. Stroud: Tempus Publishing. p. 24. ISBN 0752419102.