Here is my wishlist/checklist:
- 160 pages from the old GURPS Martial Arts updated to 4th edition
- 22 pages of combat galore from GURPS Swashbucklers (maneuvers, styles, weight, speed, range...)
- 14 pages of other combat systems from GURPS Compendium II (actually less pages, excluding guns)
- 3 pages of underwater combat from GURPS Atlantis
- 1 page of detailed and expanded bleeding rules
- 1 page of detailed and expanded infection rules
- 1 page of detailed weapon size and scale rules
- 1 or more pages of expanded (generic) mounted combat rules
- 1 page of detailed and expanded weapons customization rules from GURPS Low Tech
- 1 page of detailed and expanded armors customization rules from GURPS Low Tech
- 1 page of detailed and expanded bow/xbow/arrows rules from GURPS Low Tech
- some more rules from GURPS Compendium II that didn't make into the Basic Set [§]
- official rules for armors damage (finally!)
- Fairbairn Close Combat Training from GURPS WWII: Hand of Steel.
- notes about Mixed Martial Arts competitions (UFC, Pride)
- expanded rules for weapons and poisons
Pyramid articles to be considered (for ideas and mechanics):
- Pyramid article about Brazilian Jiu-Jitsu
- Common Misapprehensions in Swordplay by Hugh Hancock
- Medieval and Fantasy Missile Weapons by Dan Howard
- Swashbuckling in Sidebars by Bryan Maloney
- The Western Way of War by Volker Bach
- European Martial Arts Before the Rapier by Volker Bach
- Waging the Battle Royal, Roleplaying Low-Tech Battles by Volker Bach
- Honor Most Criminal, Swordplay in Elizabethan England by Bryan John Maloney
- Eight Million Bayonets, Bayonet Fencing in GURPS WW2 by Marc Goldstein
- Now That's a Knife! Modern Blades in GURPS by Jeff Fournier
[§] Advanced shields and healing rules, weapons and armors materials, specific and partial injuries . . .