David v Goliath: Do We View The Story With A Proper Perspective?

I have never really understood why David was seen as being so brave for taking on Goliath.

The fight was not exactly hand to hand, was it?
On The History Channel, I recently saw how accurate and devastating these old time slings really were!
It would be like me in my dotage taking on a bemuscled Harlem Globe Trotter in body armour. The only issue is that I have an AK 47!