While this guide will not give exact number for every weapon, it is spot on for 95%+ of the weapons in the PHB and supplements (like Sword and Fist)

All weapons start as Medium d6/20 X2 weapons and get "points" to spend on abilities
- simple weapons get 1 point
- martial weapons get 2 points
- exotic weapons get 3 points

Upping the size category by one increases the die size by one, and decreasing the size category by one decreases the die size by one.
The die sizes are d3 <-> d4 <-> d6 <-> d8/2d4/d10 <-> d12/2d6 <-> 2d8
(as per pg. 162 of the DMG)


You can spend your points in the following ways:

• 1 point per die size increase (max two points spent)
• 1 point per threat range increase (max two points spent)
• 1 point per critical multiplier increase (max two points spent)
• 1 point for reach
• 1 point for ranged weapon (increased range increment is just extra gp cost)
• 2 points for a double-headed weapon
• 2 points to be usable with a monk's UBAB
• 3 points to threaten at both 10' and 5'
• -1 point per weapon size increase
• -1 points to require a move-equivalent action to reload, and reloading draws an AoO
• -3 points to require a standard action or longer to reload, and reloading draws an AoO

So let's try some examples from the PHB:

• Heavy Mace: medium simple weapon (d6/20 X2, 1 point)
  d6 20/X2 + 1 (increase die size) -> d8 20/X2
• Light Crossbow, small simple weapon (d4/20 X2, 1 point)
  d4 + 2 (increase die size) + 1 (increase critical range) + 1 (ranged) - 3 (SA to reload, AoO) -> d8/19-20 X2 ranged
• Light Pick, small martial weapon (d4/20 X2, 2 points)
  d4 + 2 (increased crit. multiplier) -> d4/20 X4
• Scimitar, medium martial weapon (d6/20 X2, 2 points)
  d6 + 2 (increased crit range) -> d6/18-20 X2
• Long Sword, medium martial weapon (d6/20 X2, 2 points)
  d6 + 1 (increased dis size) + 1 (increased crit range) -> d8/19-20 X2
• Greatsword, large martial weapon (d8/20 X2, 2 points)
  d8 + 1 (increased die size) + 1 (increased crit range) -> 2d6/19-20 X2
• Halberd, large martial weapon (d10/20 X2, 2 points)
  d10 + 1 (increased crit mult) + 1 (reach) -> d10/20 X3 (reach)
• Longbow, large martial weapon (d8/20 X2, 2 points)
  d8 + 1 (ranged) + 1 (increase crit mult) -> d8/20 X3 (ranged)
• Kama, Halfling, tiny exotic weapon (d3/20 X2, 3 points)
  d3 + 1 (increase die size) + 2 (usable with UBAB) -> d4 20/X2 (UBAB)
• Hammer, Gnome Hooked, medium exotic weapon (d6/20 X2, 3 points)
  d6 + 2 (double headed) + 1 (crit mult on first head)
  + 2 (crit mult second head) - 1 die size (second head)
  -> d6/d4 20/X3 X4
• Sword, Two-bladed, large exotic weapon (d8/20 X2, 3 points)
  d8 + 2 (double headed) + 1 (crit range) -> d8/d8, 19-20 X2
• Crossbow, Hand, tiny exotic weapon (d3/20 X2, 3 points)
  d3 + 1 (die size) + 1 (ranged) + 1 (crit mult) - 1 (MEA to reload and AoO) -> d4/19-20 X2 (ranged, MEA reload)