The ji (halberd) was originally a bronze weapon comprised of 2 parts. A composite weapon of a double mounting of the ge weapon (dagger-axe) and a mao (spear) on a single pole.
There is evidence this double mounting of separate weapons onto a single pole was used as early as the Shang period although it seems very rare.
Only one example was shown by Yang Hong in his book "Ancient Chinese Weapons". He said it pushes the date of ji usage back to the Shang period (17th century BC to 12th century BC) but Hong didn't want to make too much of this single example. The pictures of its in-situ excavation clearly shows the 'ji' composite mounting preserved in position with a spear above although the wooden pole had long decayed. The pole was traced as previously being only 64cm long.
The reason to not identify the ji as a notable Shang weapon is because such early bronze dagger axes were mounted on very short poles, even as short as 60cm, and it were therefore best suitable for a swinging puncture attack in close combat. The early-Shang ge weapon itself was typically a right angled blade in a triangular shape although there were refinements & variations over the Shang period. The pictured examples below are votive Ba-Shu bronzes from Sichuan dating from the Zhou period, but they show the basic form of many "archaic" ge in the Shang and into the Western Zhou.

The 'classic' archaic ge looked something like a broad triangular shaped knife attached to a pole. The very early and comparatively undeveloped bronze blade at this time has visible similarities to thin stone hafted battle-axes of the Neolithic period and these early forms followed the same simple shape (even retaining a non-functional circular hole worked into the blades). See CHF thread http://www.chinahistoryforum.com/index.php...t&p=4889006 for 2 examples of archaic forms of dagger-axes.
It may be due to such short poles that the Shang ge was used as an axe or war-pick rather than a true polearm, so any combination with a spear on a short pole did not lend a great deal more utility for an expenditure of bronze.
In much later periods, such as the late East Zhou & notably the Warring States period, the combination ji was used as a polearm & it became a more common weapon. Although there are almost no examples in the Shang period the weapon was widely used in later eras. Texts on ancient weapons can show many examples in bronze of a spear mounted above a dagger-axe.
The period where the ji (combination spear & ge) was first clearly used to a notable extent is the period of the Western Zhou (12th-8th century BC). These were different to the early (Shang) and later (East Zhou) periods in that the weapons were often cast as a single bronze item with the features of both dagger-axe and spear as a unit. They then used two possible methods to attach them to the pole. Some West Zhou ji used the socketed method of the spear to attach, while others used the slot of the dagger axe and were bound via holes in the typical ge hafting method. These ji might be described then as a "spear with dagger-axe blade" or a "dagger-axe with a spear point" based on the method of their hafting.
The socketed type of ji, attached like a spear, was less common according to Yang Hong. Most the West Zhou ji halberds of this one-piece type were mounted like dagger axes by slotting into the pole, such as below.

The earliest 'combination' type (of a separate dagger-axe and spear mounted together) above was also used in the West Zhou and later this became the main type of bronze ji. In the East Zhou the single cast items seem very rare compared to the separately mounted 2 piece type.
To explain a mounting by 'slotting' there are 2 examples here, from a CHF members collection, showing how the tang slots into the pole and the cord or twine binds via the holes on the ge.

The left version is the archaic 'triangular' blade style while the right shows the more typical (& improved) East Zhou style with the upturned blade and the extension of the blade down along the pole. The triangular example is probably Western Zhou, although this basic shape was used from Shang times. Southern tribal cultures such as the Ba, Shu and Dian peoples used the obsolete archaic style ge into the Eastern Zhou period.
More pictures of the Shang and West Zhou examples of ge & ji can be seen in Yang Hong's text "Weapons in Ancient China", or else "Ancient Chinese Weapons; A collection of pictures" by Cheng Dong is another source (although this is in Chinese and not in print any more).
During the Eastern Zhou period from the 8th century BC to the 3rd century BC warriors had faced massed chariots, and then cavalry forces, as their feudal kingdoms became increasingly involved in direct military conflict.

In the early East Zhou chariots based armies were still prominent in battle. Eventually cavalry made an appearance alongside massive infantry forces in the later East Zhou. Poles were typically much longer (reaching 3-4 metres long in the Spring & Autumn period). Chariot were used throughtout the East Zhou. There is some suggestion mounted cavalry archers were important after 4th century BC military reforms of the states of Zhao however not untill the Han period was cavalry to fully replace chariot forces.
Based on contemporary East Zhou art these ancient warriors appear comparable to pikemen for the length of the longest polearms. Shorter versions of dagger-axes on 1.5m poles appear alongside the longest types. Each had its own speciality in function. Short hafted ge would be for infantry close combat while the longer poles could drag down horsemen or engage chariot crews, or attempt to disrupt tight ordered formations before entering melee.
The clearest examples portraying the 'combination' type ge, with spears, hooks and extra fittings, taken from a Eastern Zhou bronze detail below, are all of the longest pole-mounted type, while the shorter mounted dagger axes seem to require only the puncturing point to be effective when wielded one handed with a shield. As mentioned above, this perhaps explains the ji's rarity in the Shang period as chariots appear only in the late Shang period and hence long poles were less necessary. A shorter pole would allow for swifter puncturing strikes and more conventional close melee in grappling range while the long poles seem to be more like specific tools and engage over a distance. Spears mounted above dagger axes can clearly be seen below in this East Zhou bronze detail.

In the Eastern Zhou period the longer pole-mounted ji & ge would be best employed for hooking & cutting instead of a puncture strike as it require less precision to use such unwieldy weapons against a target. Manipulating the small blades point into an enemy at a distance of 3 or more metres is unlikely to work but a swing and a dragging cut could easily snag a person in its wide hooking arc.
The greater utility of a dragging cut during such an attack is reveal by 2 different design features that become standard on later dagger-axes. Blades from the Spring & Autumn onwards were set upturned at typically 100 degrees to the pole which suits a dragging cut using the inside edge and the mechanical 'pull' of an angled blade. There was also a development (which had began in the late Shang) or extending the blade below the point down the inside of the pole and the length of this blade grew over time. The dagger-axe then comes to appear like an 'r' shape with the blade extension running parallel to the pole instead of just a dagger point.
Also suited to a dragging cut, later dagger-axes of the Warring States period could have inturning points or even have serrations on the inside edge which would make horrific injuries. (see below for Warring States example*)
For more pictures of a 'typical' dagger-axe, and it's design to allow hafting to the pole, the 2 ge below show the perforations for binding, the typical 'tang' or 'axe' (nei in Chinese) that slots into the pole and the blade-point projection as well as blade extension down the pole (hu in Chinese). There are a few important differences however.

The larger example is probably late Shang or early West Zhou as it is still fairly primitive. It has few 'holes' for affixing to the pole, the tang/nei lacks a hole and the form is consistent with very early examples with the first short extension of the blade down the pole (hu) . Another hint it that this piece was once bent quite acutely and it has signs of a rough re-straightening by somebody using a vice (!). In an edition of Wenwu {Chinese: Cultural Arts} there was a site discussed that had severely bent dagger axes visibly of this same type. I have concluded it is likely related to the practice of 'killing the weapon' to send it into the next life with the owner as the mutilation must be deliberate. Such bending is more dramatic than any natural bending or damage from burial compression. One of the 'Wenwu' examples was even bent so it resembled a letter U in profile. The Wenwu site was dated 'Shang-Zhou'.
The lower smaller dagger-axe is a more 'typical' example from the Spring and Autumn period. It has the upturned and triangular-pointed appearance of such weapons. By this time chariots were being widely used in warfare. These dagger-axes first appear in the late West Zhou and I consider them the basic 'classic' form of ge.
The smaller dagger-axe here I had mounted on a 1.5m pole in the past & I can say that despite its unconvincing appearance the weapon then becomes something like a long handled tomahawk in feel. It is light, but gives the impression of very easily piercing and tearing an enemies flesh.***
Some dagger axes in the East Zhou would be mounted with 2 or 3 dagger axes set on a single pole and there are other strange and unusual forms with large rearward hooks like a scythe which also exist. (one very unique enormous hooked example can be seen at thread/post http://www.chinahistoryforum.com/index.php...t&p=4888996 "see; polearm mounted halberd; picture)
These are some example of East Zhou multiple mountings.

The Warring States period is a time where the ji double mounting was more common than ever. There were many variations on the ge & ji being used, probably due to the many independent productions of bronze weapons by the competing fuedal states where each had their own regional flavour & innovations.
This below is a lethal variation from the late Warring States period belonging to Richard Nable. *

Another serrated Warring States ge in the Shanghai museum.

These are various late period dagger-axes in the Shaanxi museum. The bottom left ge is the 'final' form of the ge, of a similar type used by the Qin & in the early West Han.



















