Most of the following data comes from this excellent myArmoury.com article, where the pollaxes are illustrated. I’ve linked to the exceptions. Weapons with a cutting edge are noted.
Approximately in chronological order:
From the Wallace Collection (A925)
Possibly French, 1400-1450. Blade length: 6 inches. Top spike: 9 inches. Total weight: 6 pounds, 10 ounces. Bladed.
From The Higgins Armory Museum (HAM # 2005.01)
German pollaxe of about 1440. Top spike length: 4 inches. Total length: 41 1/2 inches (possibly shortened). Weight: 3 pounds 8 ounces. No spike on haft. Much more, including the balance point, 4.5" from the bottom of the head, here.
From the Wallace Collection (A926)
Possibly French, about 1470. Blade length: 7 1/2 inches. Top spike: 7 5/8 inches. Total weight: 5 pounds, 8 ounces. Bladed.
From the Tower of London
European pollaxe, about 1500 Total length 70” Total weight: 6 pounds, 7 ounces
Located in a private collection
Western Europe, circa 1500. Blade length: 8 7/8 inches. Overall length: 81 7/8 inches. Weight: 5 pounds, 7 ounces. Bladed.
From the Wallace Collection (A927)
Italian, about 1530. Blade length: 9 1/4 inches. Top spike: 10 3/4 inches. Total weight: 5 pounds, 2 ounces. Bladed.
From the Wallace Collection (A928)
German, early 16th century. Blade length including socket and top spike: 17 3/8 inches. Total weight: 2 pounds, 11 ounces., but this is probably for the head without a haft. I would describe this as a halberd because the spike, langets, blade and fluke are welded into a single unit, and the Wallace Collection currently agrees. Bladed.
From the Royal Armouries, Leeds (VII.1510)
First half of 16th century. Head length: 11 1/4 inches. Overall length: 93 1/5 inches. Weight: 7 pounds, 11 ounces. Has buttspike.
Unsurprisingly, longer pollaxes weigh more, all other things being equal. The two outliers on weight are the shortest and longest.