I'm not sure you can do it globally.
This script is on the fire giant (post-levels/10000)
Code:
foreach pick in hero from BaseWep where "wCategory.Melee"
eachpick.field[wReach].value = maximum(eachpick.field[wReach].value,10)
nexteach
Obviously it just affects melee weapons as written, but you can set the where condition for something more specific.