That's a valid explanation for how wars could cause the trends in inequality, but without further evidence this is a specious argument. It also doesn't explain

That's a valid explanation for how wars could cause the trends in inequality, but without further evidence this is a specious argument. It also doesn't explain regional variations in income inequality. Look at the list of countries by income inequality: there isn't really a correlation between income inequality and "war-iness". I think wars can increase equality, but they are far from the only cause.