The warrior may fight for gold or for an immediate gain, or for something to take home for the winter to feed the family. The soldier is part of a more complex society. He's fighting for a group ethic of some sort.
Deal with the Devil if the Devil has a constituency - and don't complain about the heat.
Trade isn't about goods. Trade is about information. Goods sit in the warehouse until information moves them.
A warrior is free to be a hero and pull off daring do and the soldier is irresponsible if he does it.
Culture is how biology responds and makes its living conditions better.