It a hold over from the d20 phb 3.0 handbook
from the srd .
x2: The weapon deals double damage on a critical hit.
x3: The weapon deals triple damage on a critical hit.
x3/x4: One head of this double weapon deals triple damage on a critical hit. The other head deals quadruple damage on a critical hit.
x4: The weapon deals quadruple damage on a critical hit.
19–20/x2: The weapon scores a threat on a natural roll of 19 or 20 (instead of just 20) and deals double damage on a critical hit. (The weapon has a threat range of 19–20.)
18–20/x2: The weapon scores a threat on a natural roll of 18, 19, or 20 (instead of just 20) and deals double damage on a critical hit. (The weapon has a threat range of 18–20.)
Range Increment: Any attack at less than this distance is not penalized for range. However, each full range increment imposes a cumulative –2 penalty on the attack roll. A thrown weapon has a maximum range of five range increments. A projectile weapon can shoot out to ten range increments.
Weight: This column gives the weight of a Medium version of the weapon. Halve this number for Small weapons and double it for Large weapons.
Type: Weapons are classified according to the type of damage they deal: bludgeoning, piercing, or slashing. Some monsters may be resistant or immune to attacks from certain types of weapons.
Some weapons deal damage of multiple types. If a weapon is of two types, the damage it deals is not half one type and half another; all of it is both types. Therefore, a creature would have to be immune to both types of damage to ignore any of the damage from such a weapon.
In other cases, a weapon can deal either of two types of damage. In a situation when the damage type is significant, the wielder can choose which type of damage to deal with such a weapon.
Special: Some weapons have special features. See the weapon descriptions for details.
end of srd
Which means in traveller t20 it does not really manner. but if your were to fight space skeletons from the A2 Black pearl. therir special defense reduction
slashing/pierceing /2 meaning you half the damage.
if you were use the d20 3.5 rules skeletons would be 5/slashing,piercing which means the first 5 pts of damage from s and p weapons are not counted.
In t20 you have slashing, pierceing, bludgeoning, laser, energy , sleep, high explosive damage.
Or are you looking for the melee weapons and weapon chart.
