Ancient Greek god Ares has had many incarnations. Probably he's not the original one either. The Romans translated him as Mars. Christianity has saint Dimitrios (traslates to Jim, I don't know the full name), slaying a hostile human.
I think nowadays that religion is more distant to the masses that a general God takes care of these things now.
A Diety that transenses faiths and cultures...on the battlefield... would have to be courage. I would have said "the weapon", but holding a weapon doesn't make you a warrior, and you don't necessarily need a weapon to be a warrior.