There is a good, though a bit dusty word "милость". It's obsolete and remains only in the form of address like "your Grace" (ваша Милость), or word-pairs like "God's Grace" (Божья милость). Any modern synonym means some particular 'Grace'. So if you want an exact equivalent it would be 'милость', if you need a modern one you need to provide a more definite context.

Also a female name Grace translates as Мила.