If you beat one or more Trials of the Gods in Hard Mode, you will receive rewards. There are four rewards in total. Earning all four automatically unlocks a fifth reward. 

The rewards are as follows (in the order in which they are given): 
For the first Hard Mode Trial you beat, you'll receive the Sword of the Duat
For the second Hard Mode Trial you beat, you'll receive the Sekhem scepter 
For the third Hard Mode Trial you beat, you'll receive the Ammit shield
For the fourth Hard Mode Trial you beat, you'll receive the Jackal's Gaze bow

If you earn all four rewards, you will also automatically receive the Revenge of Anubis outfit. 
  
The rewards will be available in-game and can be equipped through the Gear menu. 

If you have any questions, feel free to get in touch!