One day Sayyidina Rasuli Akram (PBUH) was sitting in the Masjid Nabvi and Hazrat Jibreel Alaihi Salaam brought this Dua' to Rasulullah Sall Allahu alaihi wa Aalihi wa Sallim. He said that in addition to a lot of Fadhaail [favors] in this Dua', the reciter of Dua Ganjul Arsh gets three things from Allahu ta 'ala. Firstly, Allah Subhaana Hoo gives him rizq [livelihood] from the ghayb [unknown sources], and thirdly, whoever recites Dua Ganjul Arsh his enemies will not be able to overcome him. He will be superior to them.
The person who does jihad will have the upper hand. He goes on a journey, he will come back with all his things. He will be safe from the shaat of shaytaan.
He will be safe from all the bad things and insects and other things on earth and all the bad things in the skies. If a person writes Dua Ganjul Arsh out and drinks it using rain water, he will get help for various diseases. If a person suffers from an unknown illness for which the worldly doctors can find no cure and he writes it [with permission of a True Shaykh, with Zafran [saffron] and washes it and drinks it for twenty one  days he will get health from that Bi Ithnillah. If he doesn't have children, he will get children with the help of this Dua'.
Dua Ganjul Arsh