If it is possible, Weapon Knowledge ability should require Armor of God and add +3 Strength on any weapon requirements check. Icon of Weapon Knowledge in Abilities Tree should be placed above Armor of God and icons of Oaken Skin, Think like the Enemy, Praetorian, Shield Bearer, Shield Master abilities should be moved one cell to the right. Also it is better to change name of Weapon Knowledge ability to Perseverance or Tenacity.

Justification for the change:
1) Weapon Knowledge is too overpowered because it allows to use heavy veapons by character with only 1 Strength.
2) Weapon Knowledge is too far on current Abilities Tree in case you are going to use automatic weapons on character with low Strength (you will need this ability as fast as possible then).
3) Weapon Knowledge can also be very helpful if you want to create a character with low Strength and to use Rifles/Shotguns, which can require 7 or even 8 Strength.
4) Weapon Knowledge ability according to its icon and blue color seems to be closer to a "body development" branch of Abilities Tree, which starts from Armor of God.