Source: Unearthed Arcana 73 - Feats

You’ve trained in the effective use of shields. You gain the following benefits:

  • Increase your Strength, Dexterity, or Constitution score by 1, to a maximum of 20.
  • You gain proficiency with shields.
  • In combat, you can don or doff a shield as the free object interaction on your turn.
  • If you have the Spellcasting or Pact Magic feature, you can use a shield as a spellcasting focus.