> The real problem is when we move from 1000 archers with light bows, to 1000 archers with heavy medieval bows...
And ancient battles often had more than 1000 archers. Thermopylae probably had 5,000 professional archers. That's 25,000+ arrows in the sky, focused on one area. There's no question that it would block out the sun to some degree, but how much?