For each 2 ST above the required weapon ST, you gain +1 damage. Example:
This bonus automatically applies to any melee or thrown weapon, but to take advantage of it for missile weapons, you must acquire a weapon expressly built to take advantage of the extra strength. For example: A ST16 figure will only have the +3 damage on a horse bow if he acquires one specifically made for extra ST, i.e., a stronger pull. A ST15 figure will get the +2 damage on a boomerang when they acquire a heavier/larger boomerang.