Source: Unearthed Arcana 15 - Feats

You master the shortsword, longsword, scimitar, rapier, and greatsword. You gain the following benefits when using any of them:

• You gain a +1 bonus to attack rolls you make with the weapon.

• On your turn, you can use your reaction to assume a parrying stance, provided you have the weapon in hand. Doing so grants a +1 bonus to your AC until the start of your next turn or until you're not holding the weapon.

• When you make an opportunity attack with the weapon, you have advantage on the attack roll.