Each weapon has a Mastery property, granting it special abilities. That property is usable only by a character who has a feature, such as Weapon Mastery, that unlocks the property for the character. To use the Mastery feature on a weapon, that weapon must meet the Mastery's prerequisite.
Martial classes gain the Weapon Master Feat at 2nd-level for free. All characters may choose to take the Weapon Master Feat when they have the option to choose a feat.
Mastery save DC = 8 + your proficiency bonus + your Strength or Dexterity modifier (your choice)
Choose two options from the Weapon Mastery list to apply to your weapons. The weapon mastery applies to any weapon you wield that meets the prerequisites. You may only apply one weapon mastery to the same attack. At the end of each long rest, you may choose to change one or both of your chosen weapon masteries to another.
You may take this feat one additional time to gain two more Weapon Masteries.
Cleave
Prerequisite: Melee Weapon, Heavy Property
If you hit a creature with a melee attack using this weapon, you can make an attack roll with the weapon against a second creature within 5 feet of the first that is also within your reach. On a hit, the second creature takes the weapon’s damage, but don’t add your ability modifier to that damage, unless that modifier is negative. You can make this extra attack only once per turn.
Flex
Prerequisite: Strength of 18 or higher and Two-Handed or Heavy Property
You may use any weapon that has the two-handed or heavy properties as if they did not have these properties.
Flurry
Prerequisite: Light or Finesse Property
Once per turn, when you miss with an attack, you may make one additional attack against the same target.
Graze
Prerequisite: Melee Weapon, Heavy Property
If your attack roll with this weapon misses a creature, you can deal damage to that creature equal to the ability modifier you used to make the attack roll. This damage is the same type dealt by the weapon, and the damage can’t be increased in any way, other than increasing the ability modifier.
Nick
Prerequisite: Light Property
When you take the attack action with any weapon wielded in one hand, you may make an additional attack using this weapon as part of the same attack action.
Push
Prerequisite: Heavy, Two-Handed, or Versatile Property
If you hit a creature with this weapon, you can push the creature up to 10 feet away from you if it is no more than one size larger than you.
Sap
Prerequisite: No Other Properties
If you hit a creature with this weapon, you can give that creature Disadvantage on its next attack roll before the start of your next turn..
Slow
Prerequisite: None
If you hit a creature with this weapon and deal damage to the creature, you can reduce its Speed by 10 feet until the start of your next turn. If you hit the creature more than once with this property, the Speed reduction doesn’t exceed 10 feet.
Topple
Prerequisite: Heavy, Reach, or Versatile Property
If you hit a large or smaller creature with this weapon, you can to force the creature to make a Constitution saving throw with a DC equal to 8 + your Proficiency Bonus + the ability modifier you used to make the attack roll. On a failed save, the creature has the Prone condition.
Vex
Prerequisite: Ammunition, Finesse, or Light Property
If you hit a creature with this weapon and deal damage to the creature, you have Advantage on your next attack roll against that creature before the end of your next turn.
Graceful
Prerequisite: Does not have Finesse Property and does not deal Bludgeoning damage, 18 Dexterity
You may use this weapon as if it has the Finesse property.
Brace
Prerequisite: Reach
Other creatures provoke an opportunity attack from you when they enter the reach you have with this weapon.
Daze
Prerequisite: Heavy or Bludgeoning damage
When you hit a creature with this attack and deal damage, you can make the target unable to take reactions until the start of its next turn.
Duelling Stance
Prerequisite: Not wielding a shield
On your turn, you can choose to forego one attack with this weapon to increase your AC by a number equal to your proficiency bonus until start of your next turn
Opening Attack
Once per turn, when you hit a creature with this attack you can to force the creature to subtract 1d4 from the next saving throw it makes before the end of your next turn.
Whip Mastery
Prerequisite: Whip
If you hit a creature with this weapon, you may immediately grapple it or move it 5 feet towards you using the weapon. The target may escape the grapple by succeeding on a strength check with a DC equal to 8 + you proficiency bonus + your attack modifier. While a creature is grappled by your whip in this way, you cannot use this weapon.
Rush
Prerequisite: Polearm
Before making an attack on your turn, you can spend one mastery die to immediately move in a straight line towards a target within 15 feet of you without provoking attacks of opportunity.
Mighty Strike
Prerequisite: heavy and two-handed
When taking the Attack action, you can choose to forego one attack to gain advantage on your next attack. That attack scores a critical hit on 19-20.
Parry
Prerequisite: slashing damage, versatile, not wearing a shield
As a reaction to being targeted by a weapon attack, you can attempt to parry the blow by adding 1d4 to your AC against that attack.