https://www.gamesdiner.com/wp-content/uploads/sites/14/2019/11/GLAIVE_Mini_v2_3_for_GURPS_4e.pdf

Dueling Halberd recreation for optimized builds:
10 lbs (+4 damage, 13 ST)
Center Grip (-2 ST)
Two-Handed (+1 damage, -2 ST)
Long (Reach 2, -1 damage)
Pick (-1 sw damage; 1 side is pick, other is axe)

Result: Upgraded Dueling Halberd: sw+4 cut, thr+4 imp, sw+3 imp, ST 9†, Reach 1-2, Parry 0, 10 lbs
In comparison to Dueling Halberd in Low-Tech: +1 thrust damage, -3 ST, unpenalized Parry, no time to swap hands. It's improvement to one of the best weapons in game. For optimizers and munchkins alike.

Variant modifications:
May be decreased to 7 lbs (+3 damage, ST12) or 5 lbs (+2 damage, ST11)
May be increased to 15 lbs (+5 damage, ST15) or 20 lbs (+6 damage, ST17) or 30 lbs (+7 damage, ST20)
May be made non-Long for more damage in close quarters (-0 instead of -1 damage and Reach 2 instead of Reach 1)
May be made Very Long (-2 damage instead of -1; Reach 3 instead of 2) - aka full-sized Halberd that can attack in every turn
May be Stabber (+2 thr damage), if blade is truely superb, as good as on bastard swords and fencing weapons
May be Long Thruster (+3 thr damage, -3 sw damage), if making "a spear that can chop" (e.g. Hewing Spear/Atgeir) instead of "axe that can stab"

Semibalanced or Unbalanced are not worth it - parrying and attacking on same turn gets impossible, and for Reach 2+ Unbalanced makes weapon unready after attacks

Halberds:
Upgraded Breaching Halberd: sw+5 cut, thr+5 imp, sw+4 imp, ST 9†, Reach 1, Parry 0, 10 lbs
Upgraded Dueling Halberd: sw+4 cut, thr+4 imp, sw+3 imp, ST 9†, Reach 1-2, Parry 0, 10 lbs
Upgraded Halberd: sw+3 cut, thr+3 imp, sw+2 imp, ST 9†, Reach 1-3, Parry 0, 10 lbs

Upgraded Light Breaching Halberd: sw+4 cut, thr+4 imp, sw+3 imp, ST 8†, Reach 1, Parry 0, 7 lbs
Upgraded Light Dueling Halberd: sw+3 cut, thr+3 imp, sw+2 imp, ST 8†, Reach 1-2, Parry 0, 7 lbs
Upgraded Light Halberd: sw+2 cut, thr+2 imp, sw+1 imp, ST 8†, Reach 1-3, Parry 0, 7 lbs

Upgraded Heavy Breaching Halberd: sw+6 cut, thr+6 imp, sw+5 imp, ST 11†, Reach 1, Parry 0, 15 lbs
Upgraded Heavy Dueling Halberd: sw+5 cut, thr+5 imp, sw+4 imp, ST 11†, Reach 1-2, Parry 0, 15 lbs
Upgraded Heavy Halberd: sw+4 cut, thr+4 imp, sw+3 imp, ST 11†, Reach 1-3, Parry 0, 15 lbs

Upgraded Very Heavy Breaching Halberd: sw+7 cut, thr+7 imp, sw+6 imp, ST 13†, Reach 1, Parry 0, 20 lbs
Upgraded Very Heavy Dueling Halberd: sw+6 cut, thr+6 imp, sw+5 imp, ST 13†, Reach 1-2, Parry 0, 20 lbs
Upgraded Very Heavy Halberd: sw+5 cut, thr+5 imp, sw+4 imp, ST 13†, Reach 1-3, Parry 0, 20 lbs

Upgraded Extremely Heavy Breaching Halberd: sw+8 cut, thr+8 imp, sw+7 imp, ST 16†, Reach 1, Parry 0, 30 lbs
Upgraded Extremely Heavy Dueling Halberd: sw+7 cut, thr+7 imp, sw+6 imp, ST 16†, Reach 1-2, Parry 0, 30 lbs
Upgraded Extremely Heavy Halberd: sw+6 cut, thr+6 imp, sw+5 imp, ST 16†, Reach 1-3, Parry 0, 30 lbs

Other:
Upgraded Breaching Atgeir: sw+2 cut, thr+8 imp, sw+1 imp, ST 9†, Reach 1, Parry 0, 10 lbs
Upgraded Dueling Atgeir: sw+1 cut, thr+7 imp, sw+0 imp, ST 9†, Reach 1-2, Parry 0, 10 lbs
Upgraded Atgeir: sw+0 cut, thr+6 imp, sw-1 imp, ST 9†, Reach 1-3, Parry 0, 10 lbs

Upgraded Light Tactical Axe: sw+1 cut, thr+1 imp, sw+0 imp, ST 10, Reach 1, Parry 0, 3 lbs
Upgraded Tactical Axe: sw+2 cut, thr+2 imp, sw+1 imp, ST 11, Reach 1, Parry 0, 5 lbs
Upgraded Unbalanced Light Tactical Axe: sw+3 cut, thr+1 imp, sw+2 imp, ST 10, Reach 1, Parry U, 3 lbs
Upgraded Unbalanced Tactical Axe: sw+4 cut, thr+2 imp, sw+3 imp, ST 11, Reach 1, Parry U, 5 lbs