In ancient Hindu texts, it is mentioned that God gave boons to many Devtas, Asurs, Manavs, Gandharvs etc as per the tap or bhakti done by them. Doing hard tap for many many years was the way to get the boon or so-called vardaan from Trinity of Gods. Out of the Trinity, Lord Brahma was the soft target and most of the tapasvis used to do tapasya for Lord Brahma. Convincing Lord Shiva to get the boon is the most difficult. Hence very few like Ravan, Arjun etc were able to awake Shiv from his Dhyan and get the boon.
BOON / VARDAAN - Transfer of Technology
But what are these Boons or Vardans actually are? These are nothing but the transfer of technology by God. Normally we consider boons as a kind of high-level blessings, but it's not like that. The boon may be simple but technology given is complex.
Giving the boon of Brahmastra could simply mean the transfer of technology to enrich the nuclear isotopes and further perform the process of high nuclear fission.
Giving the boon of Brahmsheer Astra could simply mean the transfer of technology to perform the process of nuclear fusion.
Giving the boon of Pashupatastra Astra could simply mean the technology of creation of antimatter weapons which could even vanish the entire solar systems in one shot.
THEORY OF GOD AND EVIL
One question may arise in our mind that why Gods gave boon even to Asurs. Ok !!!! forget it....... do you know why Americans created Osama Bin Laden and Taliban !
Ya.... just because to become hero. Americans first created Taliban and then pretend to be a Hero after killing the Osama Bin Laden. Why we call 9/11 was an inside job.
Same case is with the God, God gives boon to Asurs so that Asurs can create mayhem, destruction and chaos. And God can become hero in the eyes of us after defeating the Asurs.
This process will repeat again and again. Gameplay between God and Evil will continue forever. We are just the puppets.
Actually, God is not opposite to Evil. Both complete each other. Both are the sides of coin. One is incomplete without other. Just like DC comic series' Batman will never kill the Joker. Similarly, God will never end the evil.