You are granted with a temporary boost to your agility.  Once a day, you can grasp at the power within to increase your Dexterity ability score by 2 (no upper limit), and have an advantage to any Dexterity Ability check, for 1 hour.  Once you have felt the power of this blessing, you cannot do so again until you have taken a long rest.  

You have received a blessing, or a special boon, from a very powerful creature.  Likely, you have accomplished a momentous task for this entity, or they are pleased with how you have displayed great courage or selfless humility, or you have simply done something truly amazing that catches the attention of both gods and mortals.  The reasons for being granted a blessing or boon are many.  Remember, however, these special considerations can be taken just as easily as they are given.