I had an idea of how to model the fact that beginners are less apt at using certain weapons over other ones (i.e. swinging a baseball bat is easier than punching someone with your bare hands) and that some weapons are more dangerous than others (wooden training swords vs actual sharpened swords). I present two weapon properties: difficult and dangerous.
Difficult: The weapon is difficult to master and misplaced in the hands of beginners. You gain disadvantage 1 on all attack rolls including this weapon, unless you have the feat Attack Specialization or Martial Focus for this weapon.
Dangerous: If you roll an exceptional success on an attack with this weapon, you may deal 10 of the resulting damage as lethal damage, instead of inflicting a bane or interrupting concentration.
For WL adjustment I thought of -1 for Difficult, and +1 for Dangerous. What do you think?