The fix says "Throwing weapons can no longer take damage, and are dropped when shot at 100% condition." I'm a little confused by the wording. Does this mean the player drops the throwing weapon when attempting to throw a weapon in 100% condition? Or an equipped throwing weapon that takes a hit from enemy fire is dropped?

The latter. When a weapon is dropped after being shot it's almost always broken, what this change does is make it so that if you shoot a throwing weapon out of a guy's hand it drops at full condition instead.