Weapon specialization
Prerequisite Fighter level 6th
You are a master with one weapon, and your skill with it is legendary. Choose one type of weapon from the list of weapons on page XXX of the PHB. You gain the following benefits while you wield this weapon:
- You gain +1 to hit and +2 to damage with weapons of this type.
- When you score a critical hit with this weapon your opponent must succeed in a Constitution save (DC 8 + your proficiency + your Strength or Dexterity modifier) or be staggered by the blow, suffering disadvantage to all attacks and ability checks made until the end of that creatures next turn. In addition, the staggered creature can’t take reactions.
- You have advantage on checks and saves to disarm you of your weapon.
You may change the weapon you selected when you learnt this feat, by using the training downtime activity.
NB: The 'staggered' on a critical hit ability plays nice with the Champions extended crit range. Its not an OP condition (disadv on attack rolls and ability checks and no reactions).
Fighters get to pick this up at 6th level with their bonus 6th level ASI. For featless games, just slot this ability into the fighter chassis at 6th level (in place of the ASI).
I would allow taking it multiple times, but I wouldn't allow changing one you already took. It seems odd that one might forget how to be a master with a weapon, or only be able to master a single weapon at a time.