When I first saw Arjuna Alter attacking by sending energy waves in the form of a horse, I thought it was a neat nod to Kalki, Vishnu's tenth and final avatar that's generally depicted as a white horse mounted by a warrior wielding a fiery sword and is basically the harbinger of the end of Kali Yuga. One can't deny the similarities with Arjuna Alter, who's powered by almost all of the Hindu deities and whose weapon is the sword of Mahapralaya.
But that theory kinda fell off when Karna became Super Karna, since in that form, the Hero of Charity is powered by Vishnu and Shiva thanks to Rama and Ashwatthaman.