BloodRawEngine
Video Game Engine of War
According to developer statements, Asura, along with the other "seven dieties", are originally a sort of species of demigods with cyborg-like characteristics and/or enhancements or something, whom are, judging from Asura being called a general, some sort of elite military class or something. Augus, Asura's master, is at least confirmed as it, but looking at other characters like Yasha, they have alot of the same characteristics to their designs.
As for the arms, I think it plays directly into the amount of power Asura's harnessing through his 'rage', which, after 12,000 years of manifesting while he was imprisoned, has surfaced as some sort of non-abstract power. Best I can tell, it's his "Hulk-Out". That last part is mostly my guess anyway, but taking into account that he managed to kill a planet-sized Buddha guy with what looked like Hokuto Hyakuretsu Ken times a billion, it makes sense so far.
As for the voices, I happen to really like Yasha's.