You have trained with one weapon so much that you pretty much hate all other weapons.
Select a weapon your class has proficiency with when you choose this feat. All other weapons, weather you have proficiency with them or not, are treated as if you had no proficiency with them. Unarmed strikes ignore this and cannot be selected as weapon of choice.
Gain expertise with selected weapon, doubling proficiency bonus with weapon.
Selected weapon cannot roll below 10 on attack roll to determine if the attack hits. Loose this advantage if grappled or if immobile though magical means.
Feats that add weapon proficiencies such as Weapon Master ignore this feat entirely, allowing those weapons to have regular proficiency bonuses. These weapons are not allowed to be selected by this feat.
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