You’ve learned the advanced techniques of shield wielding. Your shield is no longer just a means of defense but has become an extension of your body :

• You can use your shield hand to use any non weapon item (e.g. a torch or spellcasting focus).
• You can use your shield hand for grappling.
• You can use your shield hand to make gestures for somatic spells.

This feat does not enable you to make any weapon related actions you wouldn't be able to do with a shield equipped (e.g. Two-Handed attacks or Two-Weapon Fighting).