3.2.1. Weapons which strike with sufficient force can score a hit and/or Injury to the Target Area.
I have fought for several years, and this line seems to be the most worried about and misunderstood part of the rules.
I know many experienced fighters who will take any direct hit, even if it may not have "sufficient force" for fear of being called "rhino hide"
In fencing they have an exact measurement of force for what is considered a hit.
Do we have a definite answer here, or are we forever doomed to this problem?