Halberts differ very little from the bill, being like them conſtructed both for puſhing and cutting: a halbert conſiſts of three parts, the ſpear, or ſometimes a kind of ſvvord blade for puſhing, an ax, or hatchet for ſtriking and cutting, and a flook or hook for pulling down faſcines, in the attack of trenches, or temporary fortifications.
Source: wiktionary